Regional Atmospheric Dynamics of Water on Mars

Abstract

The investigation of water on Mars continues to be a quintessential objective in planetary exploration since water represents a critical link to Mars’ past and present climate, geology, and its potential for habitability. Direct observations of water at the regional scale is limited, and the distribution and behavior of water in the planetary boundary layer remains an outstanding question. The research in this dissertation investigates the radiative and dynamical processes governing the regional water cycle on Mars. Using global and mesoscale atmospheric models, simulations of the regional water circulation revealed a highly non-homogeneous local distribution of water that is strongly modulated by diurnal transport. Terrain-following air parcels forced along the slopes of the Tharsis volcanoes and the steep canyon walls of Valles Marineris significantly impact the local water concentration and the associated conditions for cloud formation in these regions. An investigation of water ice fogs inside Valles Marineris showed significant variability between the local atmospheric environment inside versus outside the canyon. Formation of water ice clouds is possible in Valles Marineris, but their formation is highly influenced by radiative feedbacks forced by the thermal properties of the underlying surface. An evaluation of the potential influences of the atmosphere on recurring slope lineae (RSL) activity revealed an upper limit of ~1 µm per sol for the quantity of water that can be extracted from the atmosphere through deliquescence. Ongoing efforts to understand how regional atmospheric dynamics govern the distribution of water in the planetary boundary layer represent a significant step towards a comprehensive understanding of the water cycle on Mars.