AOKI Shohei / Dept. of Solar System Sciences, ISAS
It is well known that Hydrogen Chloride (HCl) plays an important role in the atmosphere of the terrestrial planets, such as ozone depletion in the Earth atmosphere and cloud formation in the Venus atmosphere. Recently, ESA's ExoMars Trace Gas Orbiter (TGO) discovered a small amount of HCl in the Mars atmosphere. This study aims to understand the source and sink of HCl by further analysis of the TGO data. We show that a particular increase of HCl abundances in the southern summer season is annually repeated, which suggests that dust plays an important role in the formation of HCl, since dust abundances in the Mars atmosphere are relatively high in the southern summer season. We also show that the shapes of the water vapor and HCl altitude profiles are strikingly similar, which suggests that water vapor and ice clouds also play an important role in the production and loss of HCl. Moreover, we find that HCl rapidly decreases at the end of the southern summer season, which requires a strong unknown destruction process of HCl. Further study is needed to reveal the global picture of the Cl cycle on Mars including the interaction between Cl-compounds on the surface and HCl in the atmosphere.
Read the full article here, "ISAS GATE"
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