SMuK 2021 – scientific programme
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EP: Fachverband Extraterrestrische Physik
EP 6: Planets and small Objects
EP 6.2: Talk
Thursday, September 2, 2021, 11:30–11:45, H8
Atmospheric processes affecting methane on Mars — •John Lee Grenfell1, Fabian Wunderlich1,2, Miriam Sinnhuber3, Konstantin Herbst4, Ralph Lehmann5, Markus Scheucher2,6, Stefanie Gebauer1, Gabriele Arnold1, and Heike Rauer1,2,7 — 1Institut für Planetenforschung (PF), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany — 2Technische Universität Berlin (TUB), Germany — 3Karlsruhe Institute of Technology (KIT), Germany — 4Kiel University (CAU), Germany — 5Alfred Wegener Institute (AWI), Potsdam, Germany — 6Now at: NASA Jet Propulsion Laboratory (JPL), Pasadena, USA — 7Freie Universität Berlin (FUB), Germany
We investigate a range of atmospheric phenomena concerning their potential to address the Martian methane lifetime discrepancy. This refers to the over-estimate of the modelled lifetimes compared to observations by a factor of up to 600. We apply a newly developed atmospheric photochemical model where we vary in a Monte Carlo approach the chemical rate and eddy mixing coefficients within their uncertainties. Atmospheric pathways are identified and quantified in which methane is oxidized to its stable products. We also investigate the effect of air shower events due to galactic cosmic rays and solar cosmic rays. Our results suggest that the current uncertainty in chemical rates and transport together with seasonal changes in the water column and recently observed high abundances of chlorine in the Martian atmosphere can together account for a factor of 27.7 lowering (within 2-sigma) in the modelled Mars methane lifetime.