37th DPS Meeting, 4-9 September 2005
Session 27 Mars IV
Oral, Tuesday, September 6, 2005, 4:20-6:00pm, Music Concert Hall

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[27.07] Photochemistry of Mars Atmosphere and Its Variations

V. A. Krasnopolsky (Catholic University of America)

Three types of models have been developed to study Mars photochemistry. A steady-state model for global-mean conditions is the only way to calculate abundances of long living species (H2, O2, and CO). There are some differences between the latest models published a decade ago and the recent experimental data. Our model involves heterogeneous loss of odd hydrogen on the water ice aerosol and removes or reduces this disagreement. The model with heterogeneous loss probabilities of 0.01 for H, 1 for OH, 0.1 for HO2, and 10-4 for H2O2 results in the CO and O2 mixing ratios of 7.2x10-4 and 1.4x10-3, respectively. Steady-state models for local conditions address to the MGS/TES data on temperature profiles, H2O, and dust and ice aerosol. Models for 8 seasonal points uniformly spread over the martian year and for 13 latitudes with a step of 10 degrees for each season have been calculated assuming the only heterogeneous reaction of loss of H2O2 on water ice with probability of 3x10-4. Results of these models are in good agreement with the recent observations of the O2 dayglow at 1.27 \mum and O3 and H2O2 abundances. Seasonal-latitudinal maps of the O2 dayglow intensity and the O3 and H2O2 abundances are made using the calculated values. The third type of models is time-dependent model for local conditions. These models show that odd hydrogen quickly converts to H2O2 at nighttime, and chemistry is switched off while association of O, heterogeneous loss of H2O2, and eddy diffusion continue. This results in significant changes in the global-mean and local steady-state models discussed above, and these changes have been properly made. Calculated diurnal variations of Mars photochemistry agree with the measured variations of the O2 dayglow at 1.27 \mum.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.