Revealing a High Water Abundance in the Upper Mesosphere of Mars with ACS onboard TGO

Abstract

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Reappraising the Production and Transfer of Hydrogen Atoms From the Middle to the Upper Atmosphere of Mars at Times of Elevated Water Vapor

“…Water vapor vertical distribution has long remained a missing product of Mars' observations. Until recently, the SPICAM infrared spectrometer onboard Mars Express has been the only asset to regularly survey water vapor vertical distribution (Fedorova et al, 2009(Fedorova et al, , 20182021;Maltagliati et al, 2011Maltagliati et al, , 2013 using solar occultation mode, a technique that provides both sensitive (between 1 and 10 parts-per-million in volume, ppmv, in H 2 O volume mixing ratio, vmr) and vertically resolved (3-5 km vertical sampling) measurements. The enhanced presence of water vapor at high altitude during southern summer was already evidenced in some of these works, but SPICAM occultation coverage is hampered by Mars Express highly elliptical orbit, forcing an uneven temporal and latitudinal sampling, as well as by its limited detection capability.…”

“…The ACS data used in this study can be found in Belyaev (2021). The data produced by our model can be found in Montmessin (2022).…”