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Climatology of non-condensable species (O2 and CO) on Mars based on two Martian years of ACS-NIR TGO occultation measurements

Abstract : The molecular oxygen (O2) and carbon monoxide (CO) are non-condensable species of the Martian atmosphere. Their mixing ratio responds to the condensation and sublimation of CO2 from the polar caps, resulting in seasonal variations of its abundance in polar regions. Since 2018, the near-infrared channel (NIR) of the Atmospheric Chemistry Suite (ACS) onboard the Trace Gas Orbiter measured the O2 and CO density at altitudes of 0-60 km based on 0.76 µm and 1.57 µm bands, respectively, by solar occultations. We provide the long-term monitoring of the vertical distribution of these species for 2 Martian years from Ls=163° of MY34 to the Ls=180° of MY36. We report the averaged mixing ratio for CO of ~950 ppm and for O2 of~1800 ppm at altitudes 0-40 km and latitudes from 45°S to 45°N with averaged ratio O2/CO∼~2. We found a strong enrichment of both species near the surface during the southern winter and spring in middle and high southern latitudes with a layer of 3000-4000 ppm (for CO) at 10-20 km corresponding to local depletion of CO2. At equinoxes, both in the northern and southern spring, we found an increase of CO mixing ratio above 50 km to 3000-4000 ppmv explained by the downwelling flux of the Hadley circulation on Mars. We will study seasonal and spatial variations of both species and their ratio during the TGO measurements as well as interannual variability.
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https://hal-insu.archives-ouvertes.fr/insu-03775188
Contributor : Catherine Cardon Connect in order to contact the contributor
Submitted on : Monday, September 12, 2022 - 1:34:37 PM
Last modification on : Wednesday, September 14, 2022 - 3:29:44 AM

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  • HAL Id : insu-03775188, version 1

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Anna Fedorova, François Forget, Alexander Trokhimovskiy, Franck Montmessin, Franck Lefèvre, et al.. Climatology of non-condensable species (O2 and CO) on Mars based on two Martian years of ACS-NIR TGO occultation measurements. 44th COSPAR Scientific Assembly, Jul 2022, Athens, Greece. ⟨insu-03775188⟩

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