atmosphere modeling iv, chemistry and aerosols
TRANSCRIPT
![Page 1: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/1.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Atmosphere Modeling IV, Chemistry and Aerosols
Presented by Louisa Emmons, ACOM
Chemistry-Climate WG Co-Chairs: Louisa Emmons, Xiaohong Liu
WACCM WG Co-Chairs: Rolando Garcia, Jessica Neu
Software Engineer: Francis Vitt
CAM-chem Liaison: Simone Tilmes
WACCM Liaison: Mike Mills
![Page 2: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/2.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Chemistry is needed to represent atmospheric composition for radiative forcing: (CO2), CH4, O3, H2O and secondary aerosols
Importance of Chemistry and Aerosols for Climate
Chemistry and aerosols interact with the climate system, -> need to be described well in climate models
IPCC, AR5 Report (2013)
![Page 3: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/3.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Poor air quality is a major health issue
Health Burden of Global Air Pollution is Enormous
(7+ million premature deaths due to air
pollution per year !!)
![Page 4: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/4.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Simulation of atmospheric composition requires many components
![Page 5: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/5.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Chemistry-Climate Interactions in CESM2: CAM6
![Page 6: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/6.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Chemistry-Climate Interactions in CESM2:CAM-chem or WACCM
![Page 7: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/7.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
CAM6 vs CAM-chem
Same atmosphere, physics, resolution
Different chemistry and aerosols -> emissions and coupling
• CAM6: Aerosols are calculated, using simple chemistry (“fixed” oxidants) (prescribed: N2, O2, H2O, O3, OH, NO3, HO2; chemically active: H2O2, H2SO4, SO2, DMS, SOAG)
Limited interactions between Chemistry and Climate
-> prescribed fields have to be derived using chemistry-
climate simulations – Prescribed ozone is used for radiative calculations
– Prescribed oxidants is used for aerosol formation
– Prescribed methane oxidation rates
– Prescribed stratospheric aerosols
– Prescribed nitrogen deposition
– Simplified secondary organic aerosol description
![Page 8: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/8.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Modeling Chemistry-Climate Interactions in CESM2
Surface emissions and concentrations
• emissions: anthropogenic, biogenic, biomass burning, ocean, soil, volcanoes
• surface concentrations (greenhouse gases)
Chemical mechanism: important for chemistry and aerosol production
Dry Deposition: uptake of chemical constituents by plants and soil (CLM), depending on land type, roughness of surface, based on resistance approach
Wet Deposition: uptake of chemical constituents in rain or ice (linked to precipitation, both large-scale and convective).
![Page 9: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/9.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Example: NOx Emissions
Lamarque et al., 2010
1850 1900
1950 2000
![Page 10: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/10.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Modeling Chemistry-Climate Interactions in CESM2
• Greenhouse gases are prescribed as monthly fields of CO2, CH4, O3, N2O, CFCs as lower boundary conditions. All CFCs can be combined to create effective CFC emissions.
![Page 11: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/11.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Modeling Chemistry-Climate Interactions in CESM2
Surface emissions and concentrations
• emission: anthropogenic, biogenic, biomass burning, ocean, soil, volcanoes
• surface concentrations (greenhouse gases)
Chemical mechanism: important for chemistry and aerosol production
• WACCM and CAMchem: 483 reactions and 231 solution species
• CAM6: 6 chemical reactions and 25 solution species (much simpler)
Dry Deposition: uptake of chemical constituents by plants and soil (CLM), depending on land type, roughness of surface, based on resistance approach
Wet Deposition: uptake of chemical constituents in rain or ice (linked to precipitation, both large-scale and convective).
![Page 12: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/12.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Modeling Chemistry-Climate Interactions in CESM2
![Page 13: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/13.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Young et al., Elementa, 2017
Tropospheric Ozone Chemistry
![Page 14: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/14.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Models treat each process as a separate module
Chemistry:gas-phase kinetics,
photolysis, aerosol formation,
heterogeneous reactions
Surface Emissions AnthropogenicBiomass burning
Land / Ocean / Snow / Ice
Transport:Advection
boundary layer mixing, diffusion
Vertically-distributed Emissions
Aircraft (NO, BC)Lightning NO
Dry DepositionBiogenicEmissions
Cloud Processes:Convective transportAqueous chemistry
Wet deposition
![Page 15: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/15.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Solution for each chemical species i
• For each compound, at each timestep, the change in concentration is the sum of the change in concentration for each process:
– Ei: Emissions
– Ci: Gas-phase-Chemistry
– Ai: Aerosol-processes
– Ti: Advection + Diffusion
– Wi: Cloud-processes (wet deposition)
– Di: Dry deposition
• For compounds with short lifetimes the order of operators can affect results
𝜕𝑐(𝑖)
𝜕𝑡= 𝑃𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑖 − 𝐿𝑜𝑠𝑠 𝑖 = 𝐸𝑖 + 𝐶𝑖 + 𝐴𝑖 + 𝑇𝑖 +𝑊𝑖 + 𝐷𝑖
![Page 16: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/16.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Modal Aerosol Model (MAM4)
Liu et al., 2016
Representation of • Sulfates, • Black Carbon• Organic Carbon,
Organic Matter (OC, SOA),
• Mineral Dust and Sea-Salt
a1a2 a3
-> changes the lifetime of BC
a4
![Page 17: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/17.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Secondary Organic Aerosol Description in WACCM and CAM-chem
Modified after C. Heald, MIT Cambridge
SOAG species
Simplified Chemistry (CAM6):• SOAG (oxygenated VOCs)
derived from fixed mass yields• no interactions with land
Comprehensive Chemistry:• SOAG formation derived from
VOCs using Volatility Basis Set (VBS) description
• 5 volatility bins• Interactive with land
emissions-> more physical approach
![Page 18: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/18.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Modeling Chemistry-Climate Interactions in CESM2
Surface concentrations and emissions
• surface concentrations (greenhouse gases)
• emission: anthropogenic, biogenic, biomass burning, ocean, soil, volcanoes
Chemical mechanism: important for chemistry and aerosol production
• WACCM and CAMchem: 417 reactions and 220 solution species
• CAM6: 6 chemical reactions and 26 solution species (much simpler)
Dry Deposition: uptake of chemical constituents by plants and soil (CLM), depending on land type, roughness of surface, based on resistance approach
Wet Deposition: uptake of chemical constituents in rain or ice (linked to precipitation, both large-scale and convective).
![Page 19: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/19.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Dry Deposition
Varies with surface type (vegetation, ocean, etc.)Key component of ozone budgetImportant for sticky and soluble gases: HNO3, CO, OVOCs, etc.
![Page 20: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/20.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Surface concentrations and emissions
Chemical mechanism: important for chemistry and aerosol production
Dry Deposition: uptake of chemical constituents by plants and soil (CLM), depending on land type, roughness of surface, based on resistance approach
Wet Deposition: uptake of chemical constituents in rain or ice (linked to precipitation, both large-scale and convective).
• Removal is modeled as a simple first-order loss process
• Xiscav is the species mass (in kg) of Xi scavenged in time
• F is the fraction of the grid box from which tracer is being removed, and λ is the loss rate.
Important processes for simulating Aerosols
Compsets define the specifics of emissions, chemistry, and deposition!
![Page 21: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/21.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
CAM-chem – Spectral Element with Regional Refinement
CAM6-chem with Spectral Element and Regional Refinement is running with ~14 km over U.S. (~1° elsewhere)
Current science goals:
• Studying air quality and health impacts in U.S.
• Evaluating importance of greater chemical complexity vs. higher horizontal resolution
ne30
CONUS ne30x8
![Page 22: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/22.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
AMWG Diagnostic Package includes WACCM and Chemistry diagnostics
![Page 23: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/23.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
User Support: CAM-Chem Wiki pagehttps://wiki.ucar.edu/display/camchem/Home
![Page 24: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/24.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
WACCM and CAM-Chem Customer Support
CGD Forum: http://bb.cgd.ucar.edu/
Mike Mills
WACCM Liaison
(303) 497-1425
Simone Tilmes
CAM-Chem Liaison
(303) 497-1445
![Page 25: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/25.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Extras
![Page 26: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/26.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
WaterSolubility
log(H)(M
/atm
)
Vola=lity,log(C*),μg/m3
COCO2
Oxidative Chemistry
Fragmentation
SVOCi
SVOCn
SOA
dry & wet depo.
of SOA and
soluble SVOC EmissionsS/IVOC,VOC
Removal by
photolysis
+Ox
Simplis=cwaysoftrea=ngthecomplexSOAlifecycle
Fi0 edtochamberdata
VOCSOASOAyield:netconversion
Vola; lityBasisSet VOC+OH,O3
2-productsBAM VOC+OH,O3
WithSolubilityaxis
VOCCAM5BASE SOGdirectlyemitsSOG
More physical approachDirect coupling to biogenic emissions changes from MEGAN-> couples SOA formation to land use and climate change
-> VBS (volatility bin scheme) only works in full chemistry version at this point
New Secondary Organic Aerosol approach in CESM2 CAM-chem and WACCM
![Page 27: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/27.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
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 SO
A
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!
![Page 28: Atmosphere Modeling IV, Chemistry and Aerosols](https://reader031.vdocuments.mx/reader031/viewer/2022020619/61e26a948a45c13c652e692f/html5/thumbnails/28.jpg)
CESM Tutorial 2019, Chemistry / Aerosols
Stratosphere-Troposphere Exchange
• Gases and aerosols are transported in stratosphere-troposphere exchange • Impact of halogen loading on stratospheric ozone (ozone hole) • Impact on climate (importance of very short-lived species)-> local changes on short time scales are important