Atmospheric ChemistryOverview and Future Challenges

Allan Gross

Danish Meteorological InstituteLyngbyvej 100 2100 Copenhagen Oslash Denmark

amp University of Copenhagen Scientific Computing Chemistry Group

Universitetsparken 5 2100 Copenhagen Oslash Denmark

CITES 2005 March 20-23 2005 Novosibirsk Russia

Background

There is a critical need for improving the available mechanistic data in Atmospheric Chemical Transport Models (ACTM) examples

ndash the chemistry of higher molecular weight organic compounds (eg aromatic and biogenic compounds)

ndash radical reactions (eg peroxy ndash peroxy radical reactions)

ndash photo-oxidation processes (quantum yields and absorption cross sections)

ndash heterogeneous processes

Furthermore due to experimental difficulties most rates are measured best near 298 K ie temperature dependence of many reactions is not well characterised (see NIST IUPAC and NASA)

Contents

With a description of the new European project GEMS as starting point the following aspects will be outlined

ndash an overview of atmospheric chemistry (boundary layer and free-troposphere)

ndash show important areas where future studies are needed eg

bull aromatic chemistry

bull alkene chemistry

ndash a comparison of some of the most frequently used lumped atmospheric chemistry mechanisms will be given (EMEP RADM2 RACM)

Examples of atmospheric environments where these lumped mechanism need to be improved

ndash biogenic environmentndash marine environment

Objectives of GEMS (EU-project 2005-09)

Some components of the system1 combines ldquoall availablerdquo remotely sensed and in-situ data to achieve

global tropospheric and stratospheric monitoring of the composition and dynamics of the atmosphere from global to regional scale covering the tropospheric and stratosphere

Satellite data and near-real time measurements

2 global data assimilation

3 Point 1 will deliver current and operational forecasted 3-dim global distributions These distributions will be used for regional air quality modelling

Develop and implement at ECMWF a new validated comprehensive and operational global data assimilationforecasting system for atmospheric composition and dynamics

GEMS Global SystemGEMS Global SystemData input (Assimilation Satellite Real-time)

Global Greenhouse

Gasses

Global Reactive Gasses

Regional

Air Quality

Global

Aerosols

Products User Service

GEMS Global System

Coo

rdin

atio

nS

ystem In

tegrationoxidants

green house gasses

boundaryconditions

oxid

ants

opti

cal

prop

erti

es

Schematic illustration of the GEMS strategy to build an integrated operational system for monitoring and forecasting the atmospheric chemistry environment Greenhouse gasses global reactive gasses global aerosols and regional air quality

Global Reac-tive Gasses

(UV-forecast)

Regional Air Quality (RAQ

modelling)

Operational deliverables

bull Current and forecasted 3-dim global distributions of atmospheric key compounds (horizontal resolution 50 km)

ndash greenhouse gases (CO2 CH4 N2O and SF6)ndash reactive gases (O3 NO3 SO2 HCHO and gradually expanded to more

species)ndash aerosols (initially a 10-parameter representation later expanded to

app 30 parameters)

bull The global assimilationforecast system will provide initial and boundary conditions for operational regional air-quality and lsquochemical weatherrsquo forecast systems across Europendash provide a methodology for assessing the impact of global climate

changes on regional air quality ndash provide improved operational real-time air-quality forecasts

CLRTAP UN Convertion on Long-Range Trans-boundary Air Polluton

GEMS Regional Air-Quality Monotoring and Forecastning PartnersIndividual 20 Institutes

V-H Peuch (co) A Dufour METEO-FR (Meacuteteacuteo-France Centre National de Recherches Meacuteteacuteorologiques)

A Manning METO-UK (The Met Office Exeter Great-Britain)

R Vautard J-P Cammas V Thouret J-M Flaud G Bergametti

CNRS-LMD (Laboratoire de Meacuteteacuteorologie Dynamique CNRS-LA (Laboratoire dAeacuterologie CNRS-LISA (Laboratoire Inter-Universitaire des Systegravemes Atmospheacuteriques)

D Jacob B Langmann MPI-M (Max-Planck Institut fuumlr Meteorologie)

H Eskes KNMI (Koninklijk Nederlands Meteorologisch Instituut)

J Kukkonen M Sofiev FMI (Finnish Meteorological Institute)

A Gross JH Soslashrensen DMI (Danmarks Meteorologiske Institut)

M Beekmann SA- UPMC (Universiteacute Pierre et Marie Curie Service drsquoAeacuteronomie)

C Zerefos D Melas NKUA (Laboratory of Climatology and Atmospheric Environment University of Athens)

M Deserti E Minguzzi ARPA-SM (ARPA Emilia Romagna Servizio IdroMeteorologico)

F Tampieri A Buzzi ISAC (Institute of Atmospheric Sciences and Climate Consiglio Nazionale delle Ricerche)

L Tarrason L-A Breivik DNMI (Det Norske Meteorologisk Institutt)

H Elbern H Jakobs FRIUUK (Rheinisches Institut fuumlr Umweltforschung Universitaumlt Koumlln)

L Rouil INERIS (Institut National de lrsquoEnvironnement Industriel et des Risques)

JKeder JSantroch CHMI (Czech Hydrometeorological Institute)

FMcGovern BKelly EPAI (Irish Environmental Protection Agency)

WMill PIEP (Polish Institute of Environmental Protection)

DBriggs ICSTM (Imperial College of Science Technology and Medicine London)

Models Within RAQ Sub-Project

Contribution Models and Partners

Target species Data assimilation NRT ForecastE P

Re-analyses simul E P

MOCAGE METEO-FR Ozone and precursors (RACM) aerosol components (ORISAM)

ENVISAT MOPITT OMI IASI surface data

P and E E

BOLCHEM CNR-ISAC Ozone and precursors (CB-IV or SAPRC90)

Surface and profile data

P then E P case studies

EURAD FRIUUK Ozone and precursors (RACM) aerosol components (MADE)

SCIAMACHY MOPITT surface data

P then E _____

CHIMERE CNRS and SA_UPMC

Ozone and precursors (EMEP or SAPRC90) aerosol components (ORISAM)

SCIAMACHY Surface and profile data

P P

SILAM FMI Chemically inert aerosols of arbitrary size spectrum

_____ P P year 2000

MATCH FMI Ozone and precursors (EMEP) aerosol components (MONO32)

_____ P P year 2000

CAC DMI Ozone and precursors (RACM) and sulphurDMS aerosol components

_____ P P case studies

MM5-UAMV NKUA Ozone and precursors (CB-IV) _____ P P case studies

EMEP metno Ozone and precursors (EMEP) aerosol components (MM32)

MERIS and MODIS for PM information

P P 2005

REMO MPI-M Ozone and precursors (RADM2) _____ _____ P

UMAQ-UKCA UKMO Ozone and precs aerosol comp _____ P _____

E run at ECMWF P run at partner institute

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Background

There is a critical need for improving the available mechanistic data in Atmospheric Chemical Transport Models (ACTM) examples

ndash the chemistry of higher molecular weight organic compounds (eg aromatic and biogenic compounds)

ndash radical reactions (eg peroxy ndash peroxy radical reactions)

ndash photo-oxidation processes (quantum yields and absorption cross sections)

ndash heterogeneous processes

Furthermore due to experimental difficulties most rates are measured best near 298 K ie temperature dependence of many reactions is not well characterised (see NIST IUPAC and NASA)

Contents

With a description of the new European project GEMS as starting point the following aspects will be outlined

ndash an overview of atmospheric chemistry (boundary layer and free-troposphere)

ndash show important areas where future studies are needed eg

bull aromatic chemistry

bull alkene chemistry

ndash a comparison of some of the most frequently used lumped atmospheric chemistry mechanisms will be given (EMEP RADM2 RACM)

Examples of atmospheric environments where these lumped mechanism need to be improved

ndash biogenic environmentndash marine environment

Objectives of GEMS (EU-project 2005-09)

Some components of the system1 combines ldquoall availablerdquo remotely sensed and in-situ data to achieve

global tropospheric and stratospheric monitoring of the composition and dynamics of the atmosphere from global to regional scale covering the tropospheric and stratosphere

Satellite data and near-real time measurements

2 global data assimilation

3 Point 1 will deliver current and operational forecasted 3-dim global distributions These distributions will be used for regional air quality modelling

Develop and implement at ECMWF a new validated comprehensive and operational global data assimilationforecasting system for atmospheric composition and dynamics

GEMS Global SystemGEMS Global SystemData input (Assimilation Satellite Real-time)

Global Greenhouse

Gasses

Global Reactive Gasses

Regional

Air Quality

Global

Aerosols

Products User Service

GEMS Global System

Coo

rdin

atio

nS

ystem In

tegrationoxidants

green house gasses

boundaryconditions

oxid

ants

opti

cal

prop

erti

es

Schematic illustration of the GEMS strategy to build an integrated operational system for monitoring and forecasting the atmospheric chemistry environment Greenhouse gasses global reactive gasses global aerosols and regional air quality

Global Reac-tive Gasses

(UV-forecast)

Regional Air Quality (RAQ

modelling)

Operational deliverables

bull Current and forecasted 3-dim global distributions of atmospheric key compounds (horizontal resolution 50 km)

ndash greenhouse gases (CO2 CH4 N2O and SF6)ndash reactive gases (O3 NO3 SO2 HCHO and gradually expanded to more

species)ndash aerosols (initially a 10-parameter representation later expanded to

app 30 parameters)

bull The global assimilationforecast system will provide initial and boundary conditions for operational regional air-quality and lsquochemical weatherrsquo forecast systems across Europendash provide a methodology for assessing the impact of global climate

changes on regional air quality ndash provide improved operational real-time air-quality forecasts

CLRTAP UN Convertion on Long-Range Trans-boundary Air Polluton

GEMS Regional Air-Quality Monotoring and Forecastning PartnersIndividual 20 Institutes

V-H Peuch (co) A Dufour METEO-FR (Meacuteteacuteo-France Centre National de Recherches Meacuteteacuteorologiques)

A Manning METO-UK (The Met Office Exeter Great-Britain)

R Vautard J-P Cammas V Thouret J-M Flaud G Bergametti

CNRS-LMD (Laboratoire de Meacuteteacuteorologie Dynamique CNRS-LA (Laboratoire dAeacuterologie CNRS-LISA (Laboratoire Inter-Universitaire des Systegravemes Atmospheacuteriques)

D Jacob B Langmann MPI-M (Max-Planck Institut fuumlr Meteorologie)

H Eskes KNMI (Koninklijk Nederlands Meteorologisch Instituut)

J Kukkonen M Sofiev FMI (Finnish Meteorological Institute)

A Gross JH Soslashrensen DMI (Danmarks Meteorologiske Institut)

M Beekmann SA- UPMC (Universiteacute Pierre et Marie Curie Service drsquoAeacuteronomie)

C Zerefos D Melas NKUA (Laboratory of Climatology and Atmospheric Environment University of Athens)

M Deserti E Minguzzi ARPA-SM (ARPA Emilia Romagna Servizio IdroMeteorologico)

F Tampieri A Buzzi ISAC (Institute of Atmospheric Sciences and Climate Consiglio Nazionale delle Ricerche)

L Tarrason L-A Breivik DNMI (Det Norske Meteorologisk Institutt)

H Elbern H Jakobs FRIUUK (Rheinisches Institut fuumlr Umweltforschung Universitaumlt Koumlln)

L Rouil INERIS (Institut National de lrsquoEnvironnement Industriel et des Risques)

JKeder JSantroch CHMI (Czech Hydrometeorological Institute)

FMcGovern BKelly EPAI (Irish Environmental Protection Agency)

WMill PIEP (Polish Institute of Environmental Protection)

DBriggs ICSTM (Imperial College of Science Technology and Medicine London)

Models Within RAQ Sub-Project

Contribution Models and Partners

Target species Data assimilation NRT ForecastE P

Re-analyses simul E P

MOCAGE METEO-FR Ozone and precursors (RACM) aerosol components (ORISAM)

ENVISAT MOPITT OMI IASI surface data

P and E E

BOLCHEM CNR-ISAC Ozone and precursors (CB-IV or SAPRC90)

Surface and profile data

P then E P case studies

EURAD FRIUUK Ozone and precursors (RACM) aerosol components (MADE)

SCIAMACHY MOPITT surface data

P then E _____

CHIMERE CNRS and SA_UPMC

Ozone and precursors (EMEP or SAPRC90) aerosol components (ORISAM)

SCIAMACHY Surface and profile data

P P

SILAM FMI Chemically inert aerosols of arbitrary size spectrum

_____ P P year 2000

MATCH FMI Ozone and precursors (EMEP) aerosol components (MONO32)

_____ P P year 2000

CAC DMI Ozone and precursors (RACM) and sulphurDMS aerosol components

_____ P P case studies

MM5-UAMV NKUA Ozone and precursors (CB-IV) _____ P P case studies

EMEP metno Ozone and precursors (EMEP) aerosol components (MM32)

MERIS and MODIS for PM information

P P 2005

REMO MPI-M Ozone and precursors (RADM2) _____ _____ P

UMAQ-UKCA UKMO Ozone and precs aerosol comp _____ P _____

E run at ECMWF P run at partner institute

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Contents

With a description of the new European project GEMS as starting point the following aspects will be outlined

ndash an overview of atmospheric chemistry (boundary layer and free-troposphere)

ndash show important areas where future studies are needed eg

bull aromatic chemistry

bull alkene chemistry

ndash a comparison of some of the most frequently used lumped atmospheric chemistry mechanisms will be given (EMEP RADM2 RACM)

Examples of atmospheric environments where these lumped mechanism need to be improved

ndash biogenic environmentndash marine environment

Objectives of GEMS (EU-project 2005-09)

Some components of the system1 combines ldquoall availablerdquo remotely sensed and in-situ data to achieve

global tropospheric and stratospheric monitoring of the composition and dynamics of the atmosphere from global to regional scale covering the tropospheric and stratosphere

Satellite data and near-real time measurements

2 global data assimilation

3 Point 1 will deliver current and operational forecasted 3-dim global distributions These distributions will be used for regional air quality modelling

Develop and implement at ECMWF a new validated comprehensive and operational global data assimilationforecasting system for atmospheric composition and dynamics

GEMS Global SystemGEMS Global SystemData input (Assimilation Satellite Real-time)

Global Greenhouse

Gasses

Global Reactive Gasses

Regional

Air Quality

Global

Aerosols

Products User Service

GEMS Global System

Coo

rdin

atio

nS

ystem In

tegrationoxidants

green house gasses

boundaryconditions

oxid

ants

opti

cal

prop

erti

es

Schematic illustration of the GEMS strategy to build an integrated operational system for monitoring and forecasting the atmospheric chemistry environment Greenhouse gasses global reactive gasses global aerosols and regional air quality

Global Reac-tive Gasses

(UV-forecast)

Regional Air Quality (RAQ

modelling)

Operational deliverables

bull Current and forecasted 3-dim global distributions of atmospheric key compounds (horizontal resolution 50 km)

ndash greenhouse gases (CO2 CH4 N2O and SF6)ndash reactive gases (O3 NO3 SO2 HCHO and gradually expanded to more

species)ndash aerosols (initially a 10-parameter representation later expanded to

app 30 parameters)

bull The global assimilationforecast system will provide initial and boundary conditions for operational regional air-quality and lsquochemical weatherrsquo forecast systems across Europendash provide a methodology for assessing the impact of global climate

changes on regional air quality ndash provide improved operational real-time air-quality forecasts

CLRTAP UN Convertion on Long-Range Trans-boundary Air Polluton

GEMS Regional Air-Quality Monotoring and Forecastning PartnersIndividual 20 Institutes

V-H Peuch (co) A Dufour METEO-FR (Meacuteteacuteo-France Centre National de Recherches Meacuteteacuteorologiques)

A Manning METO-UK (The Met Office Exeter Great-Britain)

R Vautard J-P Cammas V Thouret J-M Flaud G Bergametti

CNRS-LMD (Laboratoire de Meacuteteacuteorologie Dynamique CNRS-LA (Laboratoire dAeacuterologie CNRS-LISA (Laboratoire Inter-Universitaire des Systegravemes Atmospheacuteriques)

D Jacob B Langmann MPI-M (Max-Planck Institut fuumlr Meteorologie)

H Eskes KNMI (Koninklijk Nederlands Meteorologisch Instituut)

J Kukkonen M Sofiev FMI (Finnish Meteorological Institute)

A Gross JH Soslashrensen DMI (Danmarks Meteorologiske Institut)

M Beekmann SA- UPMC (Universiteacute Pierre et Marie Curie Service drsquoAeacuteronomie)

C Zerefos D Melas NKUA (Laboratory of Climatology and Atmospheric Environment University of Athens)

M Deserti E Minguzzi ARPA-SM (ARPA Emilia Romagna Servizio IdroMeteorologico)

F Tampieri A Buzzi ISAC (Institute of Atmospheric Sciences and Climate Consiglio Nazionale delle Ricerche)

L Tarrason L-A Breivik DNMI (Det Norske Meteorologisk Institutt)

H Elbern H Jakobs FRIUUK (Rheinisches Institut fuumlr Umweltforschung Universitaumlt Koumlln)

L Rouil INERIS (Institut National de lrsquoEnvironnement Industriel et des Risques)

JKeder JSantroch CHMI (Czech Hydrometeorological Institute)

FMcGovern BKelly EPAI (Irish Environmental Protection Agency)

WMill PIEP (Polish Institute of Environmental Protection)

DBriggs ICSTM (Imperial College of Science Technology and Medicine London)

Models Within RAQ Sub-Project

Contribution Models and Partners

Target species Data assimilation NRT ForecastE P

Re-analyses simul E P

MOCAGE METEO-FR Ozone and precursors (RACM) aerosol components (ORISAM)

ENVISAT MOPITT OMI IASI surface data

P and E E

BOLCHEM CNR-ISAC Ozone and precursors (CB-IV or SAPRC90)

Surface and profile data

P then E P case studies

EURAD FRIUUK Ozone and precursors (RACM) aerosol components (MADE)

SCIAMACHY MOPITT surface data

P then E _____

CHIMERE CNRS and SA_UPMC

Ozone and precursors (EMEP or SAPRC90) aerosol components (ORISAM)

SCIAMACHY Surface and profile data

P P

SILAM FMI Chemically inert aerosols of arbitrary size spectrum

_____ P P year 2000

MATCH FMI Ozone and precursors (EMEP) aerosol components (MONO32)

_____ P P year 2000

CAC DMI Ozone and precursors (RACM) and sulphurDMS aerosol components

_____ P P case studies

MM5-UAMV NKUA Ozone and precursors (CB-IV) _____ P P case studies

EMEP metno Ozone and precursors (EMEP) aerosol components (MM32)

MERIS and MODIS for PM information

P P 2005

REMO MPI-M Ozone and precursors (RADM2) _____ _____ P

UMAQ-UKCA UKMO Ozone and precs aerosol comp _____ P _____

E run at ECMWF P run at partner institute

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
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Objectives of GEMS (EU-project 2005-09)

Some components of the system1 combines ldquoall availablerdquo remotely sensed and in-situ data to achieve

global tropospheric and stratospheric monitoring of the composition and dynamics of the atmosphere from global to regional scale covering the tropospheric and stratosphere

Satellite data and near-real time measurements

2 global data assimilation

3 Point 1 will deliver current and operational forecasted 3-dim global distributions These distributions will be used for regional air quality modelling

Develop and implement at ECMWF a new validated comprehensive and operational global data assimilationforecasting system for atmospheric composition and dynamics

GEMS Global SystemGEMS Global SystemData input (Assimilation Satellite Real-time)

Global Greenhouse

Gasses

Global Reactive Gasses

Regional

Air Quality

Global

Aerosols

Products User Service

GEMS Global System

Coo

rdin

atio

nS

ystem In

tegrationoxidants

green house gasses

boundaryconditions

oxid

ants

opti

cal

prop

erti

es

Schematic illustration of the GEMS strategy to build an integrated operational system for monitoring and forecasting the atmospheric chemistry environment Greenhouse gasses global reactive gasses global aerosols and regional air quality

Global Reac-tive Gasses

(UV-forecast)

Regional Air Quality (RAQ

modelling)

Operational deliverables

bull Current and forecasted 3-dim global distributions of atmospheric key compounds (horizontal resolution 50 km)

ndash greenhouse gases (CO2 CH4 N2O and SF6)ndash reactive gases (O3 NO3 SO2 HCHO and gradually expanded to more

species)ndash aerosols (initially a 10-parameter representation later expanded to

app 30 parameters)

bull The global assimilationforecast system will provide initial and boundary conditions for operational regional air-quality and lsquochemical weatherrsquo forecast systems across Europendash provide a methodology for assessing the impact of global climate

changes on regional air quality ndash provide improved operational real-time air-quality forecasts

CLRTAP UN Convertion on Long-Range Trans-boundary Air Polluton

GEMS Regional Air-Quality Monotoring and Forecastning PartnersIndividual 20 Institutes

V-H Peuch (co) A Dufour METEO-FR (Meacuteteacuteo-France Centre National de Recherches Meacuteteacuteorologiques)

A Manning METO-UK (The Met Office Exeter Great-Britain)

R Vautard J-P Cammas V Thouret J-M Flaud G Bergametti

CNRS-LMD (Laboratoire de Meacuteteacuteorologie Dynamique CNRS-LA (Laboratoire dAeacuterologie CNRS-LISA (Laboratoire Inter-Universitaire des Systegravemes Atmospheacuteriques)

D Jacob B Langmann MPI-M (Max-Planck Institut fuumlr Meteorologie)

H Eskes KNMI (Koninklijk Nederlands Meteorologisch Instituut)

J Kukkonen M Sofiev FMI (Finnish Meteorological Institute)

A Gross JH Soslashrensen DMI (Danmarks Meteorologiske Institut)

M Beekmann SA- UPMC (Universiteacute Pierre et Marie Curie Service drsquoAeacuteronomie)

C Zerefos D Melas NKUA (Laboratory of Climatology and Atmospheric Environment University of Athens)

M Deserti E Minguzzi ARPA-SM (ARPA Emilia Romagna Servizio IdroMeteorologico)

F Tampieri A Buzzi ISAC (Institute of Atmospheric Sciences and Climate Consiglio Nazionale delle Ricerche)

L Tarrason L-A Breivik DNMI (Det Norske Meteorologisk Institutt)

H Elbern H Jakobs FRIUUK (Rheinisches Institut fuumlr Umweltforschung Universitaumlt Koumlln)

L Rouil INERIS (Institut National de lrsquoEnvironnement Industriel et des Risques)

JKeder JSantroch CHMI (Czech Hydrometeorological Institute)

FMcGovern BKelly EPAI (Irish Environmental Protection Agency)

WMill PIEP (Polish Institute of Environmental Protection)

DBriggs ICSTM (Imperial College of Science Technology and Medicine London)

Models Within RAQ Sub-Project

Contribution Models and Partners

Target species Data assimilation NRT ForecastE P

Re-analyses simul E P

MOCAGE METEO-FR Ozone and precursors (RACM) aerosol components (ORISAM)

ENVISAT MOPITT OMI IASI surface data

P and E E

BOLCHEM CNR-ISAC Ozone and precursors (CB-IV or SAPRC90)

Surface and profile data

P then E P case studies

EURAD FRIUUK Ozone and precursors (RACM) aerosol components (MADE)

SCIAMACHY MOPITT surface data

P then E _____

CHIMERE CNRS and SA_UPMC

Ozone and precursors (EMEP or SAPRC90) aerosol components (ORISAM)

SCIAMACHY Surface and profile data

P P

SILAM FMI Chemically inert aerosols of arbitrary size spectrum

_____ P P year 2000

MATCH FMI Ozone and precursors (EMEP) aerosol components (MONO32)

_____ P P year 2000

CAC DMI Ozone and precursors (RACM) and sulphurDMS aerosol components

_____ P P case studies

MM5-UAMV NKUA Ozone and precursors (CB-IV) _____ P P case studies

EMEP metno Ozone and precursors (EMEP) aerosol components (MM32)

MERIS and MODIS for PM information

P P 2005

REMO MPI-M Ozone and precursors (RADM2) _____ _____ P

UMAQ-UKCA UKMO Ozone and precs aerosol comp _____ P _____

E run at ECMWF P run at partner institute

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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GEMS Global SystemGEMS Global SystemData input (Assimilation Satellite Real-time)

Global Greenhouse

Gasses

Global Reactive Gasses

Regional

Air Quality

Global

Aerosols

Products User Service

GEMS Global System

Coo

rdin

atio

nS

ystem In

tegrationoxidants

green house gasses

boundaryconditions

oxid

ants

opti

cal

prop

erti

es

Schematic illustration of the GEMS strategy to build an integrated operational system for monitoring and forecasting the atmospheric chemistry environment Greenhouse gasses global reactive gasses global aerosols and regional air quality

Global Reac-tive Gasses

(UV-forecast)

Regional Air Quality (RAQ

modelling)

Operational deliverables

bull Current and forecasted 3-dim global distributions of atmospheric key compounds (horizontal resolution 50 km)

ndash greenhouse gases (CO2 CH4 N2O and SF6)ndash reactive gases (O3 NO3 SO2 HCHO and gradually expanded to more

species)ndash aerosols (initially a 10-parameter representation later expanded to

app 30 parameters)

bull The global assimilationforecast system will provide initial and boundary conditions for operational regional air-quality and lsquochemical weatherrsquo forecast systems across Europendash provide a methodology for assessing the impact of global climate

changes on regional air quality ndash provide improved operational real-time air-quality forecasts

CLRTAP UN Convertion on Long-Range Trans-boundary Air Polluton

GEMS Regional Air-Quality Monotoring and Forecastning PartnersIndividual 20 Institutes

V-H Peuch (co) A Dufour METEO-FR (Meacuteteacuteo-France Centre National de Recherches Meacuteteacuteorologiques)

A Manning METO-UK (The Met Office Exeter Great-Britain)

R Vautard J-P Cammas V Thouret J-M Flaud G Bergametti

CNRS-LMD (Laboratoire de Meacuteteacuteorologie Dynamique CNRS-LA (Laboratoire dAeacuterologie CNRS-LISA (Laboratoire Inter-Universitaire des Systegravemes Atmospheacuteriques)

D Jacob B Langmann MPI-M (Max-Planck Institut fuumlr Meteorologie)

H Eskes KNMI (Koninklijk Nederlands Meteorologisch Instituut)

J Kukkonen M Sofiev FMI (Finnish Meteorological Institute)

A Gross JH Soslashrensen DMI (Danmarks Meteorologiske Institut)

M Beekmann SA- UPMC (Universiteacute Pierre et Marie Curie Service drsquoAeacuteronomie)

C Zerefos D Melas NKUA (Laboratory of Climatology and Atmospheric Environment University of Athens)

M Deserti E Minguzzi ARPA-SM (ARPA Emilia Romagna Servizio IdroMeteorologico)

F Tampieri A Buzzi ISAC (Institute of Atmospheric Sciences and Climate Consiglio Nazionale delle Ricerche)

L Tarrason L-A Breivik DNMI (Det Norske Meteorologisk Institutt)

H Elbern H Jakobs FRIUUK (Rheinisches Institut fuumlr Umweltforschung Universitaumlt Koumlln)

L Rouil INERIS (Institut National de lrsquoEnvironnement Industriel et des Risques)

JKeder JSantroch CHMI (Czech Hydrometeorological Institute)

FMcGovern BKelly EPAI (Irish Environmental Protection Agency)

WMill PIEP (Polish Institute of Environmental Protection)

DBriggs ICSTM (Imperial College of Science Technology and Medicine London)

Models Within RAQ Sub-Project

Contribution Models and Partners

Target species Data assimilation NRT ForecastE P

Re-analyses simul E P

MOCAGE METEO-FR Ozone and precursors (RACM) aerosol components (ORISAM)

ENVISAT MOPITT OMI IASI surface data

P and E E

BOLCHEM CNR-ISAC Ozone and precursors (CB-IV or SAPRC90)

Surface and profile data

P then E P case studies

EURAD FRIUUK Ozone and precursors (RACM) aerosol components (MADE)

SCIAMACHY MOPITT surface data

P then E _____

CHIMERE CNRS and SA_UPMC

Ozone and precursors (EMEP or SAPRC90) aerosol components (ORISAM)

SCIAMACHY Surface and profile data

P P

SILAM FMI Chemically inert aerosols of arbitrary size spectrum

_____ P P year 2000

MATCH FMI Ozone and precursors (EMEP) aerosol components (MONO32)

_____ P P year 2000

CAC DMI Ozone and precursors (RACM) and sulphurDMS aerosol components

_____ P P case studies

MM5-UAMV NKUA Ozone and precursors (CB-IV) _____ P P case studies

EMEP metno Ozone and precursors (EMEP) aerosol components (MM32)

MERIS and MODIS for PM information

P P 2005

REMO MPI-M Ozone and precursors (RADM2) _____ _____ P

UMAQ-UKCA UKMO Ozone and precs aerosol comp _____ P _____

E run at ECMWF P run at partner institute

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Operational deliverables

bull Current and forecasted 3-dim global distributions of atmospheric key compounds (horizontal resolution 50 km)

ndash greenhouse gases (CO2 CH4 N2O and SF6)ndash reactive gases (O3 NO3 SO2 HCHO and gradually expanded to more

species)ndash aerosols (initially a 10-parameter representation later expanded to

app 30 parameters)

bull The global assimilationforecast system will provide initial and boundary conditions for operational regional air-quality and lsquochemical weatherrsquo forecast systems across Europendash provide a methodology for assessing the impact of global climate

changes on regional air quality ndash provide improved operational real-time air-quality forecasts

CLRTAP UN Convertion on Long-Range Trans-boundary Air Polluton

GEMS Regional Air-Quality Monotoring and Forecastning PartnersIndividual 20 Institutes

V-H Peuch (co) A Dufour METEO-FR (Meacuteteacuteo-France Centre National de Recherches Meacuteteacuteorologiques)

A Manning METO-UK (The Met Office Exeter Great-Britain)

R Vautard J-P Cammas V Thouret J-M Flaud G Bergametti

CNRS-LMD (Laboratoire de Meacuteteacuteorologie Dynamique CNRS-LA (Laboratoire dAeacuterologie CNRS-LISA (Laboratoire Inter-Universitaire des Systegravemes Atmospheacuteriques)

D Jacob B Langmann MPI-M (Max-Planck Institut fuumlr Meteorologie)

H Eskes KNMI (Koninklijk Nederlands Meteorologisch Instituut)

J Kukkonen M Sofiev FMI (Finnish Meteorological Institute)

A Gross JH Soslashrensen DMI (Danmarks Meteorologiske Institut)

M Beekmann SA- UPMC (Universiteacute Pierre et Marie Curie Service drsquoAeacuteronomie)

C Zerefos D Melas NKUA (Laboratory of Climatology and Atmospheric Environment University of Athens)

M Deserti E Minguzzi ARPA-SM (ARPA Emilia Romagna Servizio IdroMeteorologico)

F Tampieri A Buzzi ISAC (Institute of Atmospheric Sciences and Climate Consiglio Nazionale delle Ricerche)

L Tarrason L-A Breivik DNMI (Det Norske Meteorologisk Institutt)

H Elbern H Jakobs FRIUUK (Rheinisches Institut fuumlr Umweltforschung Universitaumlt Koumlln)

L Rouil INERIS (Institut National de lrsquoEnvironnement Industriel et des Risques)

JKeder JSantroch CHMI (Czech Hydrometeorological Institute)

FMcGovern BKelly EPAI (Irish Environmental Protection Agency)

WMill PIEP (Polish Institute of Environmental Protection)

DBriggs ICSTM (Imperial College of Science Technology and Medicine London)

Models Within RAQ Sub-Project

Contribution Models and Partners

Target species Data assimilation NRT ForecastE P

Re-analyses simul E P

MOCAGE METEO-FR Ozone and precursors (RACM) aerosol components (ORISAM)

ENVISAT MOPITT OMI IASI surface data

P and E E

BOLCHEM CNR-ISAC Ozone and precursors (CB-IV or SAPRC90)

Surface and profile data

P then E P case studies

EURAD FRIUUK Ozone and precursors (RACM) aerosol components (MADE)

SCIAMACHY MOPITT surface data

P then E _____

CHIMERE CNRS and SA_UPMC

Ozone and precursors (EMEP or SAPRC90) aerosol components (ORISAM)

SCIAMACHY Surface and profile data

P P

SILAM FMI Chemically inert aerosols of arbitrary size spectrum

_____ P P year 2000

MATCH FMI Ozone and precursors (EMEP) aerosol components (MONO32)

_____ P P year 2000

CAC DMI Ozone and precursors (RACM) and sulphurDMS aerosol components

_____ P P case studies

MM5-UAMV NKUA Ozone and precursors (CB-IV) _____ P P case studies

EMEP metno Ozone and precursors (EMEP) aerosol components (MM32)

MERIS and MODIS for PM information

P P 2005

REMO MPI-M Ozone and precursors (RADM2) _____ _____ P

UMAQ-UKCA UKMO Ozone and precs aerosol comp _____ P _____

E run at ECMWF P run at partner institute

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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CLRTAP UN Convertion on Long-Range Trans-boundary Air Polluton

GEMS Regional Air-Quality Monotoring and Forecastning PartnersIndividual 20 Institutes

V-H Peuch (co) A Dufour METEO-FR (Meacuteteacuteo-France Centre National de Recherches Meacuteteacuteorologiques)

A Manning METO-UK (The Met Office Exeter Great-Britain)

R Vautard J-P Cammas V Thouret J-M Flaud G Bergametti

CNRS-LMD (Laboratoire de Meacuteteacuteorologie Dynamique CNRS-LA (Laboratoire dAeacuterologie CNRS-LISA (Laboratoire Inter-Universitaire des Systegravemes Atmospheacuteriques)

D Jacob B Langmann MPI-M (Max-Planck Institut fuumlr Meteorologie)

H Eskes KNMI (Koninklijk Nederlands Meteorologisch Instituut)

J Kukkonen M Sofiev FMI (Finnish Meteorological Institute)

A Gross JH Soslashrensen DMI (Danmarks Meteorologiske Institut)

M Beekmann SA- UPMC (Universiteacute Pierre et Marie Curie Service drsquoAeacuteronomie)

C Zerefos D Melas NKUA (Laboratory of Climatology and Atmospheric Environment University of Athens)

M Deserti E Minguzzi ARPA-SM (ARPA Emilia Romagna Servizio IdroMeteorologico)

F Tampieri A Buzzi ISAC (Institute of Atmospheric Sciences and Climate Consiglio Nazionale delle Ricerche)

L Tarrason L-A Breivik DNMI (Det Norske Meteorologisk Institutt)

H Elbern H Jakobs FRIUUK (Rheinisches Institut fuumlr Umweltforschung Universitaumlt Koumlln)

L Rouil INERIS (Institut National de lrsquoEnvironnement Industriel et des Risques)

JKeder JSantroch CHMI (Czech Hydrometeorological Institute)

FMcGovern BKelly EPAI (Irish Environmental Protection Agency)

WMill PIEP (Polish Institute of Environmental Protection)

DBriggs ICSTM (Imperial College of Science Technology and Medicine London)

Models Within RAQ Sub-Project

Contribution Models and Partners

Target species Data assimilation NRT ForecastE P

Re-analyses simul E P

MOCAGE METEO-FR Ozone and precursors (RACM) aerosol components (ORISAM)

ENVISAT MOPITT OMI IASI surface data

P and E E

BOLCHEM CNR-ISAC Ozone and precursors (CB-IV or SAPRC90)

Surface and profile data

P then E P case studies

EURAD FRIUUK Ozone and precursors (RACM) aerosol components (MADE)

SCIAMACHY MOPITT surface data

P then E _____

CHIMERE CNRS and SA_UPMC

Ozone and precursors (EMEP or SAPRC90) aerosol components (ORISAM)

SCIAMACHY Surface and profile data

P P

SILAM FMI Chemically inert aerosols of arbitrary size spectrum

_____ P P year 2000

MATCH FMI Ozone and precursors (EMEP) aerosol components (MONO32)

_____ P P year 2000

CAC DMI Ozone and precursors (RACM) and sulphurDMS aerosol components

_____ P P case studies

MM5-UAMV NKUA Ozone and precursors (CB-IV) _____ P P case studies

EMEP metno Ozone and precursors (EMEP) aerosol components (MM32)

MERIS and MODIS for PM information

P P 2005

REMO MPI-M Ozone and precursors (RADM2) _____ _____ P

UMAQ-UKCA UKMO Ozone and precs aerosol comp _____ P _____

E run at ECMWF P run at partner institute

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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GEMS Regional Air-Quality Monotoring and Forecastning PartnersIndividual 20 Institutes

V-H Peuch (co) A Dufour METEO-FR (Meacuteteacuteo-France Centre National de Recherches Meacuteteacuteorologiques)

A Manning METO-UK (The Met Office Exeter Great-Britain)

R Vautard J-P Cammas V Thouret J-M Flaud G Bergametti

CNRS-LMD (Laboratoire de Meacuteteacuteorologie Dynamique CNRS-LA (Laboratoire dAeacuterologie CNRS-LISA (Laboratoire Inter-Universitaire des Systegravemes Atmospheacuteriques)

D Jacob B Langmann MPI-M (Max-Planck Institut fuumlr Meteorologie)

H Eskes KNMI (Koninklijk Nederlands Meteorologisch Instituut)

J Kukkonen M Sofiev FMI (Finnish Meteorological Institute)

A Gross JH Soslashrensen DMI (Danmarks Meteorologiske Institut)

M Beekmann SA- UPMC (Universiteacute Pierre et Marie Curie Service drsquoAeacuteronomie)

C Zerefos D Melas NKUA (Laboratory of Climatology and Atmospheric Environment University of Athens)

M Deserti E Minguzzi ARPA-SM (ARPA Emilia Romagna Servizio IdroMeteorologico)

F Tampieri A Buzzi ISAC (Institute of Atmospheric Sciences and Climate Consiglio Nazionale delle Ricerche)

L Tarrason L-A Breivik DNMI (Det Norske Meteorologisk Institutt)

H Elbern H Jakobs FRIUUK (Rheinisches Institut fuumlr Umweltforschung Universitaumlt Koumlln)

L Rouil INERIS (Institut National de lrsquoEnvironnement Industriel et des Risques)

JKeder JSantroch CHMI (Czech Hydrometeorological Institute)

FMcGovern BKelly EPAI (Irish Environmental Protection Agency)

WMill PIEP (Polish Institute of Environmental Protection)

DBriggs ICSTM (Imperial College of Science Technology and Medicine London)

Models Within RAQ Sub-Project

Contribution Models and Partners

Target species Data assimilation NRT ForecastE P

Re-analyses simul E P

MOCAGE METEO-FR Ozone and precursors (RACM) aerosol components (ORISAM)

ENVISAT MOPITT OMI IASI surface data

P and E E

BOLCHEM CNR-ISAC Ozone and precursors (CB-IV or SAPRC90)

Surface and profile data

P then E P case studies

EURAD FRIUUK Ozone and precursors (RACM) aerosol components (MADE)

SCIAMACHY MOPITT surface data

P then E _____

CHIMERE CNRS and SA_UPMC

Ozone and precursors (EMEP or SAPRC90) aerosol components (ORISAM)

SCIAMACHY Surface and profile data

P P

SILAM FMI Chemically inert aerosols of arbitrary size spectrum

_____ P P year 2000

MATCH FMI Ozone and precursors (EMEP) aerosol components (MONO32)

_____ P P year 2000

CAC DMI Ozone and precursors (RACM) and sulphurDMS aerosol components

_____ P P case studies

MM5-UAMV NKUA Ozone and precursors (CB-IV) _____ P P case studies

EMEP metno Ozone and precursors (EMEP) aerosol components (MM32)

MERIS and MODIS for PM information

P P 2005

REMO MPI-M Ozone and precursors (RADM2) _____ _____ P

UMAQ-UKCA UKMO Ozone and precs aerosol comp _____ P _____

E run at ECMWF P run at partner institute

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Models Within RAQ Sub-Project

Contribution Models and Partners

Target species Data assimilation NRT ForecastE P

Re-analyses simul E P

MOCAGE METEO-FR Ozone and precursors (RACM) aerosol components (ORISAM)

ENVISAT MOPITT OMI IASI surface data

P and E E

BOLCHEM CNR-ISAC Ozone and precursors (CB-IV or SAPRC90)

Surface and profile data

P then E P case studies

EURAD FRIUUK Ozone and precursors (RACM) aerosol components (MADE)

SCIAMACHY MOPITT surface data

P then E _____

CHIMERE CNRS and SA_UPMC

Ozone and precursors (EMEP or SAPRC90) aerosol components (ORISAM)

SCIAMACHY Surface and profile data

P P

SILAM FMI Chemically inert aerosols of arbitrary size spectrum

_____ P P year 2000

MATCH FMI Ozone and precursors (EMEP) aerosol components (MONO32)

_____ P P year 2000

CAC DMI Ozone and precursors (RACM) and sulphurDMS aerosol components

_____ P P case studies

MM5-UAMV NKUA Ozone and precursors (CB-IV) _____ P P case studies

EMEP metno Ozone and precursors (EMEP) aerosol components (MM32)

MERIS and MODIS for PM information

P P 2005

REMO MPI-M Ozone and precursors (RADM2) _____ _____ P

UMAQ-UKCA UKMO Ozone and precs aerosol comp _____ P _____

E run at ECMWF P run at partner institute

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 63

Chemical Schemes in USA-models

bull WORF-CHEM RADM2bull CMAQ CB-IV RADM2 RACM rdquoSAPRC99rdquobull CAMX CB-IV with improved isoprene chemistry SAPRC99

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
• Slide 2
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• Slide 55
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• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Slide 63

RAQ Interfaces and Communication between ECMWF and Partner Institutes

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
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• Slide 63

GEMS Summary

bull The GEMS project will develop state-of-the-art variational estimates ofndash many trace gases and aerosolsndash the sourcessinks andndash inter-continental transports

bull Later on operational analyses will be designed to meet policy makers key requirements tondash the Kyoto protocolndash the Montreal protocol andndash the UN Convention on Long-Range Trans-boundary Air

Pollution

Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Gas-Phase Chemistry Need to be Solved in Regional Air Quality Models

Formation of

1 ozone

2 nitrogen oxides

3 peroxyacetyl nitrate (PAN)

4 hydrogen peroxide

5 atmospheric acids

Need to understand chemical reactions of

1 nitrogen oxides

2 VOC

Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Chemistry of the free-troposphere

1 nitrogen oxides and its connection with

2 carbon monoxide and

3 simplest alkane ndash methane

Polluted environment we have high NOX and VOC chemistry shall also be included

Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Reaction Cycle of HOX and NOx only VOC ndash methane

+H2O

O3

HO

Hydrocarbons

hν

HCHO

HO2

products RCHO

RO2

NONO2

O3

hν

RONO2

RO+NO2

ROOHRO3NO2

RO2NO2

H2O2

H2O2

hν

HNO3

O(3P)

Hydrocarbons

Hydrocarbons

O3

H2O2 CO

RNO3

CH4

NO3

CH3O2

CO

CH3OOH

Reaction Cycle of HOX and NOx high VOCs

Nig

htt

ime

chem

HCHO

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 63

Oxidation Steps of Hydrocarbons

RH

HO

H2OR

O2

RO2

HO2

R(ONO2)

HOO2

HO2

NO

ROOH

RO

HO

RrsquoCHO

hνHO

HONO

RrsquoR

O2NO3

NO3+O2 NO2

RO3

NO2

NO3

NO2

NO3

HNO3

hν+O2

RO2

HO2

RrsquoO2

R(-H)O+RrsquoOH+O2

RO + RrsquoO+ O2

ROORrsquo+O2ROOH+RrsquoO2

Green only alkene pathRed also other end products but these react further to the given end product

RrsquoR

OO

RrsquoCHO

O

O3

C5H12

C4H

10

C6H

14

CH3C5H11

CH

3CH

3CH

4H8

C7H

16

CH3C6H13

C3H8 C9H20

CH3C8H17 C10H22

CH3C9H19 C11

H24

C12H26 C2H4

C3H6

C4H8

C5H10CH3C4H7

CH3C4H7

C4H6

C2H

2

C6H6

CH

3C6H

5

C2H

5C6H

5

(CH3)3C6H3

HCHO

C2H5CHO

(CH

3)2C

HC

HO

C3H

7CH

O

CH

3CH

O

CH

3C6H

4C2H

5

C3H7C6H5

C4H9C

HO

CH3COCH3

CH3COC4H9

CH3OH

CH3CO2CH3

CH7CH3CO2

CH3CCl

C2Cl4

CH3Cl

C2H5CO2CH3

C2H

5OH

CH

3CO

C2H

5

C6H5C

HO

CH4

C2H6

RO3

Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Gaps in Atmospheric Chemistry High Priorities

Inorganic chemistry is relatively well known

Problemsbullalkenesbullmonocyclic aromatic hydrocarbonsbullpolycyclic aromatics hydrocarbons (PAH)

The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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The Chemistry of Alkenes Reasonable Established Rate coefficients for HO-alkene reactions of most of the alkenes which have

been studies appears to be reasonable accurate

Gaps Highest Priorities

bull the data base for RO2+ RrsquoO2 RO2 + HO2 RO2 +NO2 RO2 + NO reactions and their products are very limited and complex

ndash Eg system with only 10 RO2 (no NOX) results in approximately 165 reactions

bull ozonolysis of alkenes are important in urban polluted area Example

O3 + H2C CH2 rarr rarrHCHO + H2COO OO

OH2COO 37CO+H2O 38CO2+H2 13

primary ozonide Criegee biradical

The rate and product yields of the stable Criegee biradical with NO NO2 and H2O have only been studied for the simplest carbonhydrids Higher order carbonhyrids should be investigated

Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Many of the unsaturated dicarbonyl products appear to be very photochemically active Absorption cross sections only determined from highly uncertain gas-phase measurements

Examples of compounds it is important to determine the spectra of

trans-butenedial 4-oxo-2-pentanal 3-hexene-25-dione 4-hexadienedials

OO O

O

OO O

O

(Atmospheric oxidation products from aromatics)

The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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The Chemistry of Aromatics Still Highly Uncertain

Gaps is related both to the rate constant the of aromatic chemistry and the yields of the formed products

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 61
• Slide 62
• Slide 63

Rate coefficients for HO-reactions with monocyclic aromatics

ndash only 23 aromatics have been studied

only studied by one lab

p-cymene tetralin α-methyl-styrene β-methyl-styrene β-β-dimethyl-styrene

iso-propyl-benzene o- m- p-ethyl-toluene tert-butyl-benzene indan indene

studied by more than one lab but with over all uncertainties greater than 30

ndash rate constants for only 20 of the many aromatics products of the oxidation of aromatics have been determined 14 of these are single studies

Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Rate coefficients for HO-reactions with polycyclic aromatics (PAHs)

ndash only 16 aromatics have been studied

only studied by one lab

1- 2-methyl-naphthalene 2 3-dimethyl-naphthalene acenaphthalene

flouranthene 1- 2-nitronaphthalene 2-methyl-1-nitron-aphthalene

NO2

NO2

NO2

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
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• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Slide 63

HO +PAH studied by more than one lab rate constant uncertainties for seven PAHs

biphenyl (30) fluorene (fac of 15) acenaphthene (fac of 2)

phenanthrene (fac of 2) dibenzo-p-dioxin(fac of 15) dibenzofuran (30)

O

O

anthracene one of the most abundant and important PAH in the atmosphere

anthracene

Rate highly uncertain

range (18 to 289) times 10-12 cm3 molecule-1

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Slide 63

3-methyl-phenanthrene pyrene benzo[a]flouorene

Rate coefficients for PAHs with vapor pressures greater than app 10-5 Torr (298 K) should be determined since their reaction with HO may be an improtant removal process three examples are

HO +PAH

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
• Slide 2
• Slide 3
• Slide 4
• Slide 5
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• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Slide 63

NO3 + aromatics appear unimportant in the atmosphere

Exceptions

bull a group attached to the atomatic ring have a double bound (ex indene styrene)

bull have an ndashOH group attached to the aromatic ring (ex phenols cresols)

Only studies NO3 + amp amp

phenol o- m- p-cresol m-nitro-phenol

NO2

OH OH OH

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
• Slide 2
• Slide 3
• Slide 4
• Slide 5
• Slide 6
• Slide 7
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• Slide 14
• Slide 15
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• Slide 23
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• Slide 33
• Slide 34
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• Slide 38
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• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• Slide 49
• Slide 50
• Slide 51
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Slide 63

bull O3 + aromatics have gaps but these reactions are not highly important in atmospheric chemistry

bull O(3P) + aromatics unimportant in urban atmosphere

bull Atmospheric chemistry of organic compounds sorbed on particles (heterogeneous reactions) and its reactions in aerosols even more uncertain Important

bull PAHs oxidation sorbed on particles Important

bull PAHs + HO more studies are needed

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
• Slide 2
• Slide 3
• Slide 4
• Slide 5
• Slide 6
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
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• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Slide 63

bull Non-aromatic products from the oxidation of aromatic compounds ndash additional kinetic and mechanics studies of the rates are neededndash Especially the HO initiated reactionsndash Product studies of HO + aromatics from chamber

experiments shows carbon mass losses from 30 to 50 ie quite possible that some yet unidentified reactions pathways That means the overall atmospheric oxidation mechanism of aromatics is still rather uncertain

Highest priority a study the products from the oxidation of

most important aromaticsbull toluenebull xylenes andbull trimethyl-substituted benzenes

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 63

Application of Chemistry in Atmospheric ndashChemical Transport Models

Problemsbull A ldquoComplete Mechanismrdquo would require tens of thousands of

chemical species and reactionsbull The reaction mechanisms and rates are not known for most of

thesebull The ordinary differential equation for chemical mechanisms is

very stiff ie numerical standard methods are not applicable

Way of solving itbull Using lumped chemical mechanismbull Make special ad hoc adjustments to the rate equation to remove

stiffness in the lumped mechanism rarr use a fast solver

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
• Slide 2
• Slide 3
• Slide 4
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• Slide 59
• Slide 60
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• Slide 62
• Slide 63

Correlation of the rates for NO3 with O(3P)

Correlation of the rates for NO3 with HO

(line c) addition reactions

Δ (lines a amp b) abstraction reacs

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 63

Correlation of Peroxy Peroxy Radical Reactions

Function fit depend on number of carbons Function fit depend on the rates from theand the alkyl-alkoxy substitution reactants peroxy-self-reaction rates

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
• Slide 2
• Slide 3
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• Slide 63

Lumped Atmospheric Chemical Mechanisms

Mech Abbreviation

Developed in

Number of

Species Reactions

ADOM-11 USA 47 114

CB-IV USA 27 63

RADM2 USA 63 158

SAPRC-90 USA 60 155

IVL Europe 715 1640

EMEP Europe 79 141

RACM USA 77 237

SAPRC-99 USA 74 211

Master MCH Europe 2400 7100

Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Chamber Experiment EC-237

bull Photolysis

bull NOX

bull Ethenebull Propenebull tert-2-butene

bull n-butenebull 2 3-dimethylbutenebull toulenebull m-xylene

RACM and RADM2 are tested against 21 Chamber Experimentsincluded 9 organic speciesUsed chamber Statewide Air Pollution Research Center Key species tested in the chamber NO2 NO and O3

RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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RACM better than RADM2 Ref Stockwell et al JGR 1997

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 63

RACM better than RADM2

Ref Stockwell et al JGR 1997

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
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• Slide 63

Problems With These Chamber Experiments

bull 50 or more of the total HO comes from the chamber walls (depend on the chamber)

bull Chamber walls can serve as sources or sinks for O3 NOX aldehydes and ketones

bull Photolysis maybe uncertainbull Chamber experiments are conducted at much higher species concentrations than in the atmosphere (ie have a lot of radical reactions which do not occur in the real atmosphere)

If eg EUPHORE chamber data were used these problems would be smaller

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
• Slide 2
• Slide 3
• Slide 4
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• Slide 61
• Slide 62
• Slide 63

O3

isoplets

localnoon

Ref Gross and Stockwell JAC 2004

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 61
• Slide 62
• Slide 63

O3 and HO

Scatter plots

WithoutEmissions

3 days simLocal Noon

O3

O3

HO

HO

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
• Slide 2
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• Slide 4
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HO2 and RO2

Scatter plots

WithoutEmissions

3 days simLocal Noon

HO2

HO2

RO2

RO2

Ref Gross and Stockwell JAC 2004

Δ urban rural

times neither urban nor rural

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 63

Mechanism Comparison Summarybull Compared to each other the mechanisms showed clear trends

O3 EMEP gt RACM gt RADM2 HO and HO2 RACM gt EMEP and RACM gt RADM2

RO2 EMEP gt RACM and RADM2 gt RACM

bull The mechanism comparison showed little differences between the three mechanisms equally good

However all these mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

bull However few of the simulated scenarios gave very large simulated differences between the mechanisms This showed that only one ldquotypicalrdquo scenario (which often has been considered to be sufficient) is not enough in order to make a proper mechanism comparison

Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Biogenic Chemistry

ndash Several hundreds different BVOC have been identified Most well known are ethene isoprene and the monoterpenes

ndash Isoprene is the major single emitted BVOC

ndash The BVOC emission depend highly on vegetation type

ndash BVOC emissions also contain oxygen-containing organics

Estimated global Annual BVOC Emission (Tgyear)

Isoprene Monoterpene Other VOCs

asymp 500 asymp 130 asymp 650

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

• Slide 1
• Slide 2
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• Slide 51
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Slide 63

chloroplasts

isoprene2-methyl-3-buten-2-ol

resin ducts or glands

many tissues

cell walls

flowers

cell membranes

leaves stems roots

monoterpenes

formaldehydeformic acid

acetaldehydeacetic acid

ethanol

acetone

C6-acetaldehydesC6-alcohols

100s of VOC

methanol

ethylene

(Fall 1999)

Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 61
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Some Biogenic Emitted Hydrocarbons

isoprene α-pinene β-pinene limonene α-terpinene γ-terpinene camphene

terpinolene α-phellandrene β-phellandrene myrcene ocimene Δ3-carene p-cymene

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 63

Some Oxygen-Containing Organics Biogenic Sources

3-methyl-5-hepten-2-one 3-hexenal 2-hexenal thujone methanol

ethanol n-hexanol 3-hexenol camphor linalool

HO

formaldehyde acetaldehyde acetone butanone n-hexanal

O

OH

OH

O O

O

O O O

O

OH OH

O

OH OH

O

OH

OO

2-methyl-3-buten-2-ol formic acid acetic acid 3-henenyl-acetate 1 8-cineol

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation without BVOCs (called base mix)

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 10
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• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
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• Slide 19
• Slide 20
• Slide 21
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• Slide 23
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• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Slide 63

Ref Ruppert 1999

EUPHORE Chamber Experiment and Simulation base mix + 90 ppbV α-pinene

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 61
• Slide 62
• Slide 63

EUPHORE Chamber Experiment and Simulation base mix + isoprene

Sim with RACM Sim with modified RACM

ozonetolueneethene

isopreneNO2

NO

Ref Ruppert 1999

Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Biogenic Study Summary

bull The BVOC emission inventory are calculated from land-use data The BVOCs emissions from plants are usually only given for isoprene and monoterpenes However in Kesselmeier and Staudt (Atm Env 33 23 1999) are BVOCs from other compounds than isoprene and monoterpene presented

bull How shall the split of the emissions of monoterpenes into specific species (α-pinene β-pinene limonene etc) be performed This is not clear

bull BVOC emission inventories have uncertainties of factors asymp 25-9

bull How good are the land-use data bases to describe the current BVOCndash How good are seasonal changes of vegetation describedndash How good are human changes of vegetation described

bull The understanding of biogenic chemistry is very incomplete Today only one lumped mch treat other biogenic emitted species than isoprene RACM also treat

ndash API α-pinene and other cyclic terpenes with more than one double boundndash LIM d-limonene and other cyclic diene-terpenes

bull Commonly used lumped mechanisms (CBM-IV RADM2 EMEP and RACM) do not describe the chemistry of isoprene very good

DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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DMS (DiMethyl Sulphide) Chemistry Identified Atmospheric Sulphur Compounds

HS CH3SO2OHCS2 CH3S(O)OOHCOS CH3SCH2OOHSO2 CH3S(O)2OOHH2SO4 [SULF] CH3OS(O)2OH CH3SCH3 [DMS] CH3OS(O)2OCH2

CH3S(O)CH3 [DMSO] CH3S(O)2CH3OOHCH3S(O)2CH3 [DMSO2] HOCH2S(O)2OHCH3SSCH3 [DMDS] HOCH2S(O)2CH2OHCH3SH CH3SO2ONOCH3SOH [MSEA] CH3SO2ONO2

CH3S(O)OH [MSIA]

CH3S(O)2OH [MSA] It is not an easy task to make a DMS gas-phase mechanism

A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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A gas-phase DMS mch was developed during the EU-project period This DMS mch included 30 sulphur species and 72 reactions (49 guessed amp 23 experimental rates)

Based on clean MBL scenarios the DMS ELCID mch was reduced to 21 sulphur species and 34 reactions (22 guessed amp 12 experimental rates)

DMS mch for Atm ModellingThe ELCID gas-phase mch

The ELCID mch was further reduced by lumping to 15 sulphur species and 20 reactions This mechanism was used for 3D modelling in the ELCID project

The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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The Atmospheric Box-model

In the box the following processes are solved for species i (which can be either a liquid or gas phases species)

dCidt = + chemical production ndash chemical loss

+ emission

ndash dry deposition ndash wet deposition

+ entrainment from the free troposphere to the boundary layer

+ aerosol model

+ CCN model + cloud model

Ref Gross and Baklanov IJEP 2004 22 52

Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Influence of DMS on acc mode particles in the clean MBL

DMS emission in pptVmin

AIS AIW CGS CGW EUMELI3

DMS cont Nnss 268 133 183 295 129

DMS cont Ntot

upper limit 178 972 129 233 944

DMS cont Ntot

lower limit 100 524 707 121 508

AISW Amsterdam Island SummerWinterCGSW Cape Grim SummerWinterEUMELI3 oceanografic cuise south and east of the Canary Islands

bull DMS cont Nnss DMS contribution in to accumulation mode nss aerosols bull DMS cont Ntot upper (lower) limit the upper (lower) limit of DMS contribution

in to the sea salt plus the non sea salt accumulation mode aerosols

Ref Gross and Baklanov IJEP 2004 22 51

Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Mechanism Comparison

Number of Sulphur

Species Reacs Ref

Koga and Tanaka 33 40 JAC 1992 17 201

Hertel et al 36 58 Atm Env 1994 38 2431

Capaldo and Pandis 37 71 JGR 1997 102 23251

JRC ISPRA mch 32 38 Privat comm 2002

ELCID mch 21 34 ELCID proj 2004

Mechanism adjustments bull The mechanisms is adjusted such that similar rate constants for the

DMS loss and SO2 and H2SO4 formation are usedbull Rest of the mechanisms are not changed

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 63

Concentration of DMSOX (pptV)

Contour levels from 50 to 850 pptV increment interval 50 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

2004

1992

1997 2002

1995

Ref Gross and Baklanov ITM 2004

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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• Slide 61
• Slide 62
• Slide 63

Concentration of inorganic sulphur (pptV)

Contour levels from 10 to 165 pptV increment interval 15 pptV DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1175pptV

max1532pptV

max1175pptV

max1336pptV

max1373pptV

2004 1997 2002

1992 1995

Ref Gross and Baklanov ITM 2004

Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Particle number concentration (cm-3) Accumulation mode

Contour levels from 10 to 120 cm-3 increment interval 10 cm-3 DMS emis = 036 pptmin ELCID

JRC ISPRA CapampPan

Hertel et al KogampTan

max1050pptV

max1177pptV

max1044pptV

max1185pptV

max1185pptV

2004 2002

1994 1992

1997

Ref Gross and Baklanov ITM 2004

DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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DMS Study Summarybull DMS important to include in atm modelling if aerosols and large ocean areas are

included in the model domain since DMS can roughly contribute bull from 1327 (summer period) and 313 (winter period) of the formation

of non sea salt aerosolsbull from 1018 (summer period) and 110 of the total aerosol formation

bull Too simplified DMS chemistry [DMS(g)+HO(g)-gtSO2(g)-gtH2SO4(l)] create too many new accumulation mode particles (Gross and Baklanov ITM 2004)

bull The DMS mechanism comparison showed that all five mechanism gave all most the same amount of inorganic DMSOX sulphur aerosols equally good

However all these DMS mechanisms are based on the same guessed rates and reactions ie the same amount of uncertainty

DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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DMS Summary Resent Results

bull A resent ab initioDFT study (Gross Barnes et al JPC A 2004 108 8659) shows1 DMSOH + O2 rarr DMSO + HO2 (the dominant channel)2 DMSOH + O2 rarr DMS(OH)(OO) (occur minor channel)3 DMSOH + O2 rarr CH3SOH + CH3O2 (does not occur)

However in DMS mechanisms channels 1 and 2 are often considered to be equal important and channel 3 is included

bull Simulations of DMS chamber experiments (which were performed at different temperatures and NOX concentrations) indicate that we still not fully understand the chemistry of the additional DMS+HO channel Important chemical mechanisms are missing (Gross and Barnes unpublished results)

Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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Conclusionsbull More detailed mechanisms of aromatics and peroxide reactions are

needed

bull The isoprene chemistry should been updated in the lumped mechanisms

bull If heterogeneous chemistry also is included in the ACTM many parameters used to described the mass transport of gas-phase species to aerosols and these species aerosol physics are still uncertainunknown

bull The DMS chemistry is still highly uncertain both with respect to rate constant determination and the product mechanism Furthermore the emission of DMS is poorly known

bull Better description of biogenic emissions is needed before it is meaningful to increase the chemistry of BVOC with more species than isoprene and monoterpene (personal opinion)

Has described the most important chemistry need for regional scale Atmospheric Chemistry Transport Modelling (ACTM) and has described where atmospheric chemistry still has large uncertainties

CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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CollaboratorsAtmospheric Sciencebull Senior Scientist Alexander A Baklanov Danish Meteorology Institute Denmarkbull Senior Scientist Jens H Soslashrensen Danish Meteorology Institute Denmarkbull Senior Scientist Alix Rasmussen Danish Meteorology Institute Denmarkbull Research Scientist Alexander Mahura Danish Meteorology Institute Denmark

Atmospheric Chemistrybull Research Prof William R Stockwell Desert Research Institute Reno Nevada USAbull Associate Prof I Barnes University of Wuppertal Germanybull PhD Stud Marianne Sloth University of Copenhagen Denmark and Danish

Meteorological Institute Denmark

Theoretical and Physical Chemistrybull Prof Kurt V Mikkelsen University of Copenhagen Denmarkbull Asistant Prof Balakrishan Naduvalath State University of Nevada Las Vegas USA bull PhD Stud Nuria Gonzales Garcia Universitat Autonoma de Barcelone Spainbull Research Assistant Hanne Falsig University of Copenhagen Denmark

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