Skip to Main content Skip to Navigation
Journal articles

Thermal structure and aerosols in Mars’ atmosphere from TIRVIM/ACS onboard the ExoMars Trace Gas Orbiter : validation of the retrieval algorithm

Abstract : The Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO) monitors the Martian atmosphere through different spectral intervals in the infrared light. We present a retrieval algorithm tailored to the analysis of spectra acquired in nadir geometry by TIRVIM, the thermal infrared channel of ACS. Our algorithm simultaneously retrieves vertical profile of atmospheric temperature up to 50 km, surface temperature, and integrated optical depth of dust and water ice clouds. The specificity of the TIRVIM dataset lies in its capacity to resolve the diurnal cycle over a 54 sol period. However, it is uncertain to what extent can the desired atmospheric quantities be accurately estimated at different times of day. Here we first present an Observing System Simulation Experiment (OSSE). We produce synthetic observations at various latitudes, seasons and local times and run our retrieval algorithm on these synthetic data, to evaluate its robustness. Different sources of biases are documented, in particular regarding aerosol retrievals. Atmospheric temperature retrievals are found robust even when dust and/or water ice cloud opacities are not well estimated in our OSSE. We then apply our algorithm to TIRVIM observations in April-May, 2018 and perform a cross-validation of retrieved atmospheric temperature and dust integrated opacity by comparisons with thousands of co-located Mars Climate Sounder (MCS) retrievals. Most differences between TIRVIM and MCS atmospheric temperatures can be attributed to differences in vertical sensitivity. Daytime dust opacities agree well with each other, while biases are found in nighttime dust opacity retrieved from TIRVIM at this season.
Document type :
Journal articles
Complete list of metadata
Contributor : Catherine Cardon Connect in order to contact the contributor
Submitted on : Sunday, February 6, 2022 - 4:18:48 PM
Last modification on : Thursday, April 7, 2022 - 1:58:27 PM
Long-term archiving on: : Saturday, May 7, 2022 - 6:09:28 PM


JGR Planets - 2022 - Guerlet -...
Publisher files allowed on an open archive


Distributed under a Creative Commons Attribution - NonCommercial 4.0 International License



S Guerlet, N. Ignatiev, Francois, Forget, T. Fouchet, P. Vlasov, et al.. Thermal structure and aerosols in Mars’ atmosphere from TIRVIM/ACS onboard the ExoMars Trace Gas Orbiter : validation of the retrieval algorithm. Journal of Geophysical Research. Planets, Wiley-Blackwell, 2022, 127 (2), pp.e2021JE007062. ⟨10.1029/2021je007062⟩. ⟨insu-03559369⟩



Record views


Files downloads