The effect of the Martian 2018 global dust storm on HDO as predicted by a Mars Global Climate Model

Loïc Rossi (1) , Margaux Vals (1) , Franck Montmessin (1) , Francois Forget (2) , Ehouarn Millour (2) , Anna Fedorova (3) , Alexander Trokhimovskiy (3) , Oleg Korablev (3)

1 PLANETO - LATMOS
2 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
3 IKI - Space Research Institute of the Russian Academy of Sciences

The D/H ratio is commonly used to investigate the history of water on Mars, yet the mechanisms controlling present‐day HDO behavior are poorly understood. Significant variations of the D/H ratio were first predicted on the basis of a 3D global climate model, which were later confirmed by ground‐based observations. This behaviour, consisting of lower HDO/H2O ratios in the colder regions of Mars, is related to the isotopic fractionation occurring at condensation. We leverage this previous effort and present an updated implementation, using the modern version of the model, that remains in agreement with the older version. We explore the impact of the Global Dust Storm that occurred during Martian Year 34 on HDO. Our simulations indicate that HDO is on average 40% more abundant at 100 km during the MY34 GDS year than during a regular year, with likely large consequences for the escape flux of water that year.

Domaines: Planète et Univers [physics]

Loïc Rossi, Margaux Vals, Franck Montmessin, Francois Forget, Ehouarn Millour, et al.. The effect of the Martian 2018 global dust storm on HDO as predicted by a Mars Global Climate Model. Geophysical Research Letters, 2021, 48 (7), pp.e2020GL090962. ⟨10.1029/2020GL090962⟩. ⟨insu-03166590v2⟩