Adapting GEOS_CHEM to Mars Photochemisty
Huiqun Wang1
Kelly Chance1
Daniel Jacob2
Mark Richardson3
Michael Mischna4
1 Center for Astrophysics (CFA)2 Harvard
3 CALTECH4 JPL
• 1D photochemical model for Mars
• 3D Mars GCM
• Observations of trace gases and aerosols
in the Martian atmosphere
Motivation
Mars atmospheric compositionCO2 0.955 H2O 0-70prµm
N2 0.027 O3 0-60µm-atm
Ar 0.016 H2O2 0-40ppb
O2 1.3e-3 …
CO 8.0e-4
H2 1.7e-5
He 1.0e-5
Ne 2.5e-6
Kr 3.0e-7
CH4 1.0e-81 prµm = 3.34e+18 cm-2; 1 µm-atm = 2.69e+15 cm-2 = 0.1DU
2
2
2 22 2
CO h CO O
O O M O M
CO CO O
Photochemistry in a pure CO2 atmosphere
2
2 3
O h O O
O O M O
Prediction:
CO: 7.72e-2
O2: 3.87e-2
O3: 126DU
Observation:
CO: 7.0e-4
O2: 1.3e-3
O3: < a few DU
CO2 stability problem
HOx catalytic chemistry
2H O h H OH
2
2 2
2 2
2
CO OH CO H
H O M HO M
O HO O OH
CO O CO
2
3 2
2 3
2
CO OH CO H
H O OH O
O O M O M
CO O CO
2
2 2
2 2 2 2 2
2 2
2 2
2( )
2( )
2
2 2
CO OH CO H
H O M HO M
HO HO H O O
H O h OH
CO O CO
[McElroy & Donahue, 1972; Parkinson & Hunten, 1972]
2
2 2
2 2
2
2 2
2 2
2( )
2( )
2 2
CO OH CO H
H O M HO M
HO NO NO OH
NO h NO O
O HO O OH
CO O CO
2
2 2
2 2
2 2
2
CO OH CO H
H O M HO M
HO NO NO OH
NO O O NO
CO O CO
HOx-NOx catalytic chemistry
Heterogeneous chemistry
Mars GCMs• NASA AMESC-grid, p coord, 0-80km
• GFDL A-grid, σ-p coord, 20–40 layers, 0-80km
• LMD/AOPPA-grid/spectral, σ coord, 32 layers, 0-120/240km
• Planetary WRFC-grid, σ coord, 25 or 40 layers, 0-80km
…
CO2 IR heating
Dust visible & IR heating
Surface physics
Subgrid-scale processes
CO2 cycle
Water cycle
Dust cycle
Atmospheric chemistry
SPICAM Water Vapor Column abundance [Fedorova et al., 2006]
[Perrier et al., 2006]
MEX simultaneous observations of water vapor and ozone
3D Mars photochemical model
• Lefevre et al., 2004. Three-dimensional modeling of ozone on Mars. J. Geophys. Res.,109, doi:10.1029/2004JE002268.
• Hartogh et al., 2006. A new coupled 3D-model of the dynamics and chemistry of the Martian atmosphere. DPS 2006 abstract #60.05.
• Moudden and McConnell, 2006. Three-dimensional on-line chemical modeling in a Mars general circulation model, submitted to Icarus.
GEOS_CHEM
Mars meteorology
Mars photochemistry•Kinetic reactions•Photolysis
Mars GCM LIDORTTable for J-values
Interface with MGCM• Time
Year, Day-of-Year, Planetary-second
• ConstantsCMN_GCTM: eccentricity, g0, Rplanet, Rd, Cp, …
• File formatInput Netcdf: 40 days / GCM met file
Output Bpch: restart file & diagnostics
• Grid structure64 longitudes, 36 latitudes, 25 levels
120nm – 800nm
CO2, O2, O3, H2O, Rayleigh, dust
LIDORT→Actinic Flux→Integration→Scaling
2
1
, , , ,J T P T P I d
Look-up table for J:SZA, Surface P, O3 column, H2O column, column dust, T profile type
Phot-freq Cross section Quantum yield Actinic flux
Top Related