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Thermal Structure of the Middle and Upper Atmosphere of Mars from ACS/TGO CO2 Spectroscopy
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  • Denis A. Belyaev,
  • Anna A. Fedorova,
  • Alexander Trokhimovskiy,
  • Juan Alday,
  • Oleg I Korablev,
  • Franck Montmessin,
  • Ekaterina Starichenko,
  • Kevin Sutherland Olsen,
  • Andrey Patrakeev
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 (IKI), Space Research Institute (IKI)
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Alexander Trokhimovskiy
Space Research Institute (IKI), Space Research Institute (IKI)
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Juan Alday
Open University, Open University
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Oleg I Korablev
Space Research Institute (IKI), Space Research Institute (IKI)
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Franck Montmessin
LATMOS CNRS/UVSQ/IPSL, LATMOS CNRS/UVSQ/IPSL
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Ekaterina Starichenko
Space Research Institute (IKI), Space Research Institute (IKI)
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Kevin Sutherland Olsen
University of Oxford, University of Oxford
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Andrey Patrakeev
Space Research Institute (IKI), Space Research Institute (IKI)
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Abstract

Temperature and density in the upper Martian atmosphere, above ~100 km, are key diagnostic parameters to study processes of the species’ escape, investigate the impact of solar activity, model the atmospheric circulation, and plan spacecraft descent or aerobraking maneuvers. In this paper, we report vertical profiling of carbon dioxide (CO2) density and temperature from the Atmospheric Chemistry Suite (ACS) solar occultations onboard the ExoMars Trace Gas Orbiter (TGO). A strong CO2 absorption band near 2.7 μm observed by the middle infrared spectrometric channel (ACS MIR) allows the retrieval of the atmospheric thermal structure in a large altitude range, from 20 to 180 km. We present the latitudinal and seasonal climatology of the thermal structure for 1.5 Martian years (MYs), from the middle of MY 34 to the end of MY 35. The results show the variability of distinct atmospheric layers, such as a mesopause (derived from 70 to 150 km) and homopause, changing from 80-90 km at aphelion to 100-110 km at perihelion. Some short-term homopause fluctuations are also observed depending on the dust activity.