Comparison of three photochemical mechanisms (CB4, CB05, SAPRC99) for the Eta-CMAQ air quality...
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Transcript of Comparison of three photochemical mechanisms (CB4, CB05, SAPRC99) for the Eta-CMAQ air quality...
Comparison of three photochemical mechanisms (CB4, CB05, SAPRC99) for the Eta-CMAQ air quality forecast model for
O3 during the 2004 ICARTT study
Shaocai Yu$,&, Golam Sarwar+, Rohit Mathur+, Daiwen Kang$,&, Daniel Tong$,&,
&Atmospheric Modeling Division, ARL, NOAA , RTP, NC 27711. $On assignment from Science and Technology Corporation,
+ NERL, U.S. EPA, RTP, NC 27711
Introduction (Motivation)Introduction (Motivation)
Photochemical mechanisms Critical module of air quality models 30% or more uncertainties30% or more uncertainties due to errors in reaction rate constants and yields due to errors in reaction rate constants and yields
(Russell and Dennis, 2000) (Russell and Dennis, 2000)
Three widely used photochemical mechanisms: CB4: Carbon Bond Mechanism-version IV with lumped structure approach (Gery
et al., 1989) CB05: updated version of CB4 with more inorganic reactions and organic species
(Yarwood et al., 2005) SAPRC99: different scheme (lumped molecule approach) for condensing the
organic chemistry and more detailed organic chemistry (Carter, 2000)See Table
Useful and interest: study how these three photochemical mechanisms affect the CMAQ simulation of
O3 by comparing to observations
CB05 and SAPRC: more species and reactions; better characterization of radical recycling; but need more time
Objectives
Evaluate influence of CB4, CB05 and SAPRC99 on
the spatial and temporal variations of O3 with
AIRNOW Obs over the eastern US
Examine impact of CB4, CB05 and SAPRC99 on
Eta-CMAQ simulations for O3, its gas precursors
with 2004 ICARTT field data
Model Description (Configuration)Model Description (Configuration)
Eta-CMAQ model:
Eta forecast model provides meteorological fields for CMAQ
CB4, CB05, SAPRC99: photochemical processes
Emissions processed using Emissions processed using SMOKE processing systemSMOKE processing system
12 km12 km horizontal grid resolution horizontal grid resolution
22 Vertical layers between surface and 100 22 Vertical layers between surface and 100 mbmb
This result: July 14 to August 18, 2004
Observations
EPA AIRNOW network:
Hourly O3 at 614 sites in E US.
Ground Data at Four AIRMAP sites
Model domain and surface sites (AIRNOW, AIRMAP)
AIRMAP sites
Observations
2004 ICARTT Data
Vertical profiles (O3, CO, NO, NO2, HNO3, SO2) from aircraft (P-3 and DC-8).
Surface-level data over the ocean on Ron Brown ship
Tracks of (a) P-3, (b) DC-8
P-3
DC-8
•P-3: Northeast; •DC-8: Eastern US
Results: Max 8-hr O3 at AIRNOW sites
Very close
58.8
21.5
5.3
-5.7
73.3
32.6
15.1
3.9
77.3
37.1
20.7
10.6
-10.0
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
<40 40-60 60-75 >75
O3 concentrations (ppb)
NM
B (%
)
CB4
CB05
SAPRC
Results: O3 Vertical profiles (7/14-8/15)
Models reproduced vertical structure of Obs•P3: SAPRC99>CB05>CB4>Obs•DC-8: similar to P3 although slightly close to Obs
(1) P-3
Daily Layer Means
Hei
ght (
m)
Results: CO and HNO3 Vertical profiles (7/14-8/15)
CO:Consistent Underpredictions.partly due to inadequate representation of biomass burning
effects from outside the domain
Obs>CB05~CB4>SAPRC
Daily Layer Means
HNO3:Very good
Slight underprediction
(1) P-3
Conc. (ppb)
Conc. (ppb)
Hei
ght (
m)
Results: NO2 and NO Vertical profiles (7/14-8/15)
NO2:P3: good at high altitudes
Underestimate at lower altitudesOrganic nitrate can react back to NO2 in CB05 and SAPRC
Daily Layer Means
NO:Under predictions of NO
Aircraft and lightning NO emissions are not in inventory
Results: NOy, SO2, H2O2Vertical profiles (7/14-8/15)
NOy, Consistent overestimation
SO2: Overestimation at low altitudes but good at high altitudes
Daily Layer Means
H2O2:CB4: significant overestimation
Its H2O2 formation rate is 62% higher than CB05 (Luecken et al., 2008)
CB05 and SAPRC: close to ObsCB05: slightly higher than ObsSAPRC: slightly lower than Obs
CB05 produces more new HO2, enhancing H2O2
Results: Time-series evaluation on ship
Gas species (NMB ,%)
Con
ce
ntr
atio
n
020406080
100120140160
O3 (Obs)O3 (CB4)O3 (CB05)O3 (SAPRC)
ppbv
0100200300400500600700 CO (Obs)
CO (CB4)CO (CB05)CO (SAPRC)
ppbv
010203040506070 NOy (Obs)
NOy (CB4)NOy (CB05)NOy (SAPRC)
ppbv
0
10
20
30
40 NO2 (Obs)NO2 (CB4)NO2 (CB05)NO2 (SAPRC)
ppbv
0
50
100
150 O3+NO2 (Obs)O3+NO2 (CB4)O3+NO2 (CB05)O3+NO2 (SAPRC)
ppbv
0
4
8
12
16 NO (Obs)NO (CB4)NO (CB05)NO (SAPRC)
ppbv
012345 PAN (Obs)
PAN (CB4)PAN (CB05)PAN (SAPRC)
ppbv
02468
10 SO2 (Obs)SO2 (CB4)SO2 (CB05)SO2 (SAPRC)
ppbv
0
0.4
0.8
1.2
1.6 Isoprene (Obs)Isoprene (CB4)Isoprene (CB05)Isoprene (SAPRC)
ppbv
7/14 7/24 8/3 8/137/19 7/29 8/8Time (UTC, 2004)
CB4 CB05 SAPRC
O3 24.4 36.5 42.3
O3+NO2 21.5 32.2 37.9
CO -4.3 -7.4 -13.3
NOy 43.3 37.6 16.4
NO2 -6.2 -13.9 -10.2
NO -30.6 -46.9 -46.4
PAN 28.6 24.6 -11.3
SO2 68.4 82.0 85.6
ISOP -61.3 -58.7 -60.7
Slightly better:CB4: O3, CO, NO2, NO, SO2
CB05: Isop
SAPRC: NOy, PAN
O3
NOy
NO2
NO
PAN
SO2
Isoprene
CO
O3+NO2
Results: Time-series data on ship
O3 production efficiency (N)
O3-NOz slope (Olszyna et al., 1994):Upper limit of N
SAPRC>CB05>CB4 but all are lower than ObsConsistent with O3 concentrations
Results2. Time-series evaluation at AIRMAP sites
Castle Springs (CS)
O3
NOy
NO
CO
SO2
High O3 period (721-7/23)
Low O3 period (724-7/27)
020406080
100120 O3 (Obs)
O3 (CB4)O3 (CB05)O3 (SAPRC)
ppbv
0100200300400500 CO (Obs)
CO (CB4)CO (CB05)CO (SAPRC)
ppbv
0
0.5
1
1.5NO (Obs)NO (CB4)NO (CB05)NO (SAPRC)
ppbv
0
2
4
6
8 NO2 (Obs)NO2 (CB4)NO2 (CB05)NO2 (SAPRC)
ppbv
02468
101214 NOy (Obs)
NOy (CB4)NOy (CB05)NOy (SAPRC)
ppbv
0
5
10
15
20 SO2 (Obs)SO2 (CB4)SO2 (CB05)SO2 (SAPRC)
ppbv
7/14 7/24 8/3 8/13 8/187/19 7/29 8/8time (UTC, 2004)
NO2
Results2. O3 production efficiency at AIRMAP sites (O3-NOz slope)
0
20
40
60
80
100
120
O3 (Obs)O3 (CB4)O3 (CB05)O3 (SAPRC)
0 2 4 6 8 10 12
CS
O3 (Obs)O3 (CB4)O3 (CB05)O3 (SAPRC)
0 2 4 6 8 10 12
MWO
0 2 4 6 8 10 12
O3 (Obs)O3 (CB4)O3 (CB05)O3 (SAPRC)
TF
NOz (ppb)
O3 (
pp
b)
Results2. O3 production efficiency at AIRMAP sites (O3-NOz slope)
N
O3-NOz slope:Upper limit of N
SAPRC>CB05>CB4 but all are lower than ObsConsistent with O3
concentrationsSAPRC is close to Obs
Contacts:
Brian K. Eder
email: [email protected]
www.arl.noaa.gov/
www.epa.gov/asmdnerl
ConclusionsBased on 35-day (7/14-8/18/2004) simulations over eastern U.S:
At AIRNow sites for max 8-hr O3, SAPRC has the highest O3, followed by CB05 and CB4
Consistent with the results of N
For high concentrations>75ppb, CB05 is better than CB4 and SAPRC
For concentration ranges<75 ppbv, CB4 is better (less overestimation) than CB05 and SAPRC
Vertical profiles from P-3 and DC-8: Models captured vertical structures of gaseous species (O3,CO,NOy,HNO3,H2O2 etc.) Overestimated O3: SAPRC>CB05>CB4
Consistent overestimation: NOy,
Consistent underestimation: CO, NO, NO2
H2O2: CB4 significantly overestimated but CB05 and SAPRC are close to Obs
• CB05: slightly higher than Obs; SAPRC: slightly lower than Obs)
Contacts:
Brian K. Eder
email: [email protected]
www.arl.noaa.gov/
www.epa.gov/asmdnerl
Conclusions (Continued) Results on the basis of ship time-series data:
Slightly better: CB4: O3, CO, NO2, NO, SO2
CB05: Isoprene SAPRC: NOy, PAN
Modeled upper limit of N by O3-NOz slopes on basis of ship and AIRMAP data: SAPRC (5.3 to 10.2)>CB05(4.5 to 7.5)>CB4(4.0 to 6.1)
Are consistently lower than observations (8.5 to 11.8)Background O3 conc. is ~10 ppb higher than Obs
Disclaimer
The research presented here was performed under the Memorandum of Understanding
between the U.S. Environmental Protection Agency (EPA) and the U.S. Department of
Commerce's National Oceanic and Atmospheric Administration (NOAA) and under
agreement number DW13921548. This work constitutes a contribution to the NOAA Air
Quality Program. Although it has been reviewed by EPA and NOAA and approved for
publication, it does not necessarily reflect their policies or views.
CBMIV (Operational) vs. CB05 (experimental) performance
Max 8-hr O3, CONUS, June 15-Aug. 31, 2008
• Lower bias and error with CB05 at moderate-high O3 mixing ratios• Higher error in regional statistics due to over-prediction at low mixing ratio range
- Could it be for reasons other than chemical mechanism?
Results
7/19/047/18/047/17/04
July 16-22, 2004: Evidence of effects of long range transport (Alaskan fire)
(1) MODIS (satellite) observations for AOD
(2) TOMS (satellite) observations for absorbing aerosol index
Significant underpredictions of PM2.5 by the model during July 16 to 26 are mainly due to inadequate representation of biomass burning (carbonaceous aerosol) effects from outside the domain (Alaskan fire)