1. Adapting GEOS_CHEM to Mars Photochemisty Huiqun Wang 1 Kelly Chance 1 Daniel Jacob 2 Mark Richardson 3 Michael Mischna 4 1 Center for Astrophysics (CFA) 2 Harvard 3 CALTECH 4 JPL

2. 1D photochemical model for Mars 3D Mars GCM Observations of trace gases and aerosols in the Martian atmosphere Motivation

3. Mars atmospheric composition CO 2 0.955H2OH2O0-70pr µm N2N2 0.027O3O3 0-60 µm-atm Ar0.016H2O2H2O2 0-40ppb O2O2 1.3e-3… CO8.0e-4 H2H2 1.7e-5 He1.0e-5 Ne2.5e-6 Kr3.0e-7 CH 4 1.0e-8 1 prµm = 3.34e+18 cm-2; 1 µm-atm = 2.69e+15 cm-2 = 0.1DU

4. Photochemistry in a pure CO 2 atmosphere

5. Prediction: CO: 7.72e-2 O 2 : 3.87e-2 O 3 : 126DU Observation: CO: 7.0e-4 O 2 : 1.3e-3 O 3 : < a few DU CO 2 stability problem

6. HO x catalytic chemistry [McElroy & Donahue, 1972; Parkinson & Hunten, 1972]

7. HOx-NOx catalytic chemistry Heterogeneous chemistry

8. Mars GCMs NASA AMES C-grid, p coord, 0-80km GFDL A-grid, σ-p coord, 20–40 layers, 0-80km LMD/AOPP A-grid/spectral, σ coord, 32 layers, 0-120/240km Planetary WRF C-grid, σ coord, 25 or 40 layers, 0-80km … CO 2 IR heating Dust visible & IR heating Surface physics Subgrid-scale processes CO 2 cycle Water cycle Dust cycle Atmospheric chemistry

9. SPICAM Water Vapor Column abundance [Fedorova et al., 2006] [Perrier et al., 2006] MEX simultaneous observations of water vapor and ozone

10. MEX SPICAM observations of ozone vertical profile

11. 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.

12. GEOS_CHEM Mars meteorology Mars photochemistry Kinetic reactions Photolysis Mars GCM LIDORT Table for J-values

13. Interface with MGCM Time Year, Day-of-Year, Planetary-second Constants CMN_GCTM: eccentricity, g0, Rplanet, Rd, Cp, … File format Input Netcdf: 40 days / GCM met file Output Bpch: restart file & diagnostics Grid structure 64 longitudes, 36 latitudes, 25 levels

14. 120nm – 800nm CO 2, O 2, O 3, H 2 O, Rayleigh, dust LIDORT →Actinic Flux→Integration→Scaling 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

15. Preliminary results from basic model