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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