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Revealing a High Water Abundance in the Upper Mesosphere of Mars with ACS onboard TGO
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  • Denis A. Belyaev,
  • Anna A. Fedorova,
  • Alexander Trokhimovskiy,
  • Juan Alday Parejo,
  • Franck Montmessin,
  • Oleg I Korablev,
  • Franck Lefèvre,
  • Andrey Patrakeev,
  • Kevin S. Olsen,
  • Alexey V. Shakun
Denis A. Belyaev
Space Research Institute (IKI), Space Research Institute (IKI)

Corresponding Author:[email protected]

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Anna A. Fedorova
Space Research Institute, Space Research Institute
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Alexander Trokhimovskiy
Space Research Institute (IKI), Space Research Institute (IKI)
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Juan Alday Parejo
University of Oxford, University of Oxford
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Franck Montmessin
LATMOS CNRS/UVSQ/IPSL, LATMOS CNRS/UVSQ/IPSL
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Oleg I Korablev
Space Research Institute (IKI), Space Research Institute (IKI)
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Franck Lefèvre
LATMOS, LATMOS
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Andrey Patrakeev
Space Research Institute, Space Research Institute
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Kevin S. Olsen
University of Oxford, University of Oxford
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Alexey V. Shakun
Space Research Institute (IKI), Space Research Institute (IKI)
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Abstract

We present the first water vapor profiles encompassing the upper mesosphere of Mars, 100–120 km, far exceeding the maximum altitudes where remote sensing has been able to observe water to date. Our results are based on solar occultation measurements by Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO). The observed wavelength range around 2.7 μm possesses strong CO2 and H2O absorption lines allowing sensitive temperature and density retrievals. We report a maximum H2O mixing ratio varying from 10 to 50 ppmv at 100–120 km during the global dust storm (GDS) of Martian Year (MY) 34 and around southern summer solstice of MY 34 and 35. During other seasons water remains persistently below ~2 ppmv. We claim that contributions of the MY34 GDS and perihelion periods into the projected hydrogen escape from Mars are nearly equivalent.
28 May 2021Published in Geophysical Research Letters volume 48 issue 10. 10.1029/2021GL093411