Chemistry and Aerosols performance of CESM2 WACCM / CAM-chemSimone Tilmes CCWG Liaison (tilmes@ucar.edu)

Mike Mills, Doug Kinnison, Louisa Emmons, Jean-Francois Lamarque, Andrew Gettelman, Francis Vitt,

Pedro Campuzano Jost, Jose Jimenez,CAM-chem and WACCM team

CESM Joint Chemistry Climate and Whole Atmosphere Working Group SessionTuesday June 19th, 2018

Chemistry and Aerosols Performance of CESM2 WACCM / CAM-chem

Unified vertical grid below about 50hPa

WACCM/ CAM-chem levels Comprehensive ChemistryWACCM: TSMLT1 231 species CAM-chem: TS1 221 species• Interactive volcanic sulfate in the

stratosphere• SOA volatility basic set (VBS) description

Specified ChemistryWACCM SC: 29 species CAM6: 25 speciesRequire fields from WACCMDynamicsGravity Waves in WACCM / CAM-chem

Secondary Organic Aerosol Description

Modified after C. Heald, MIT Cambridge

SOAG species

Simplified Chemistry:• SOAG derived from fixed mass

yields• no interactions with land

Comprehensive Chemistry:• SOAG formation derived from

VOCs using VBS scheme• 5 volatility bins• Interactive with land

emissions-> more physical approachAnthropogenic Source / Fires

OH

WACCM / WACCM-SC Secondary Organic Aerosols

1995-2010

PI-ControlWACCM-SC WACCM New VBS scheme

• Formation of SOA slower due to chemical processing -> reduced SOA near surface, more SOA in upper Tropics

• Removal processes included for SOAG (deposition) and SOA (photolysis) -> reduced values in high latitudes

• Net gas-particle partitioning ~140 Tg/yr, SOA lifetime 4.5 yrs.

WACCM / WACCM-SC Secondary Organic Aerosols

Biogenic Fossil fuelFires

Differences in AODVIS 1995-2010

Differences 1995-2010 SOA Burden (0-5km) WACCM SOA Trends 1990-2014

Biomassburning

Biogenic

Fossil Fuel

CESM2 Total SOA BurdenTotal SOA Burden

• Relative increase in SOA towards present day counteracted by changes in other aerosols

PI-control

CAM6 (dashed) different SSTsWACCM WACCM-SCCAM-chem

Comparison to ATom Aircraft Campaign 2016/17/18

Atmospheric Tomography MissionATom1: July 28 – August 22 2016ATom2: Jan 26 – Feb 22, 2017 ATom3: Sep 28 – Oct 26, 2017ATom4: April 24 – May 21, 2018

Pedro Campuzano Jost, Jose L. Jimenez

WACCM Simulation SDusing CMIP6 (anthro) andQFED fire (solid) emissions, CAM-chem: Finn fires (dashed)

Comparisons of OA, SO4, and BC

Comparison to ATom1 Aircraft Campaign 2016/17

Very good agreement in general, too little OA in the Northern polar region

Pedro Campuzano Jost, Jose L. Jimenez

Comparison to ATom1 Aircraft Campaign 2016/17

Pedro Campuzano Jost, Jose L. Jimenez

Comparison to ATom1 Aircraft Campaign 2016/17

Good agreement at the surface and the lower troposphere.

Overestimation in higher altitudes likely due to shortcomings in wet scavenging.

Pedro Campuzano Jost, Jose L. Jimenez

Stratospheric Ozone Column (DU)

April

October

January

July GW tuning for CAM-chemmay be needed

Observations (OMI/MLS)WACCM1 (CCMI)WACCMCAM-chem

ObservationsWACCM1WACCMWACCMWACCM CAM-chem

Total Column Ozone 63-90oS October

From Doug Kinnison

Eastern U.S.

OzonesondesWACCMCAM-Chem

900 hPa

Tropospheric Ozone

500 hPa

Western Europe

ObservationsWACCMCAM-Chem

900 hPa 500 hPa

Very good agreement in summer, high bias in winter northern latitudes

Tropospheric COApril

October

January

July

CO is reduced compared to WACCM1-> new CO emissions are lower

Observations (MOPITT)WACCM1WACCMCAM-chem

Tropospheric Column Ozone Difference to OMI/MLSCCMI Comparison (Revell et al., 2018 submitted)

ConclusionsCESM2 WACCM and CAM-chem

• Improved representation of tropospheric and stratospheric aerosols require comprehensive tropospheric and stratospheric chemistry

• Regional changes in climate (temperature and precipitation) as well as climate impacts possible compared to simplified chemistry

• Very good representation of ozone, chemistry and aerosols in the model, known shortcomings and biases still have to be addressed

Extras

Oxygenated VOC (gas)

0.38 Tg

SOA1.04 Tg

142 Tg/yr

Biogenic, anthropogenic and biomass burning VOC, SIVOC

44Tg/yr

dry

wet

dry

J SOA

wet 57 Tg/yr

72 Tg/yr12 Tg/yr

VBS Budgets 1995-2010

Net gas-particlepartitioning Depends on

J values for different chemicals

Most of it from biogenic emissions-> strongly dependent on MEGAN emissions

108Tg/yr

chem. Prod.294Tg/yr

+ OxidantsGlyoxal uptake

Lifetime: 4.5 years

Values very close to observational estimates!

Prognostic Volcanoes

Thanks to MikeMills

New SO2 database• Includes amount and

altitude of SO2 injections from eruptive volcanoes

OCS chemistry• Contributes to stratospheric

sulfate

Interactive with chemistry, radiation and dynamics• Includes interactive H2SO4

and SO4 formation• Requires comprehensive

stratospheric chemistryResults agree very well with observations

WACCM / WACCM-SC Sulfates

1995-2010

1850WACCM-SC WACCM WACCM-SC• Stratospheric sulfate is prescribed• Lower SO4 in the troposphere

through missing sources

WACCM• 1850 PI-control includes averaged

volcanoes • Transient stratospheric

distribution is variable

CESM2 Tropospheric Aerosol EvolutionTotal SOA Burden

• More tropospheric sulfate in WACCM; missing sources in WACCM-SC• Relative increase in SOA towards present day counteracted by other changes

-> increase in RESTOM-> Changes in climate can be expected with full chemistry

PI-control

CAM6 (dashed) different SSTsWACCM WACCM-SCCAM-chem

PI-control

CAM6 (dashed) different SSTsWACCM WACCM-SCCAM-chem

SO4 Burden < 200hPa

CESM2 Tropospheric Aerosol EvolutionCAM6 (dashed) different SSTsWACCM WACCM-SCCAM-chem

CAM6 (dashed) different SSTsWACCM WACCM-SCCAM-chem

Difference in Radiation between WACCM and WACCM-SC (obs. SSTs)

• More tropospheric sulfate in WACCM compared to WACCM-SC due to missing sources in WACCM-SC

• Relative increase in SOA towards present day is counteracted by stronger decrease in BC and POM, and reduced increase in SO4 and dust

-> Changes in Climate in including Chemistry can be expected

Transient CESM2 CAMchem 1850-2015 (FHIST)

Tropospheric Burden (< 200hPa)Secondary Organic Aerosols

Primary Organic Aerosols

TotalBiogenicFossil fuelBiomass burning

TotalFossil fuelBiomass burning

Differences in TS and Precipitation1850 1995-2010