Modelling the sulphur cycle on early Mars
Résumé
The presence of sulphate deposits, covering approximately 5-10% of the Martian surface (McSween, 2010), indicates significant volcanic outgassing of sulphur during Mars' early history, starting from the mid-Noachian era (Gaillard and Scallet, 2013). The resulting sulphur cycle would have had a strong influence on the Martian climate and geology, affecting the planet's ability to maintain liquid water on its surface. Previous analyses of the early Mars sulphur cycle have mostly relied on photochemical lifetimes from one-dimensional photochemical models (e.g., Johnson et al., 2009; Tian et al., 2010). Here, we make use of the Generic Planetary Climate Model, consisting of a 3D dynamical core which we have coupled, for the first time, with a complete model of SO2 and H2S photochemistry in the atmosphere of early Mars. Our model also takes into account the formation, precipitation and deposition of H2SO4 and SO2 aerosols. We provide preliminary model results on geographical variations in the surface deposition of sulphates, and on local greenhouse warming induced by volcanic SO2 emission.