Seasonal and Diurnal Variations of Orographic Clouds on Mars with EMM/EXI observations and the Mars Planetary Climate Model

Abstract

The formation of water ice clouds can significantly influence the Martian climate, although the Martian atmosphere contains low water vapor concentrations compared to terrestrial levels. The lower Martian atmosphere exhibits three global water ice cloud systems: Aphelion cloud belt (ACB), polar hoods (PHs), and orographic clouds. These clouds are associated with topography, solar heating, global atmospheric circulation, wave activity, and local convection. An appreciable amount of research has been conducted on the first two regimes (ACB and PHs) and very little attention has been given to the third regime (orographic clouds). In general, orographic clouds are observed in northern Spring and summer since they are associated with the major Martian volcanoes. Water ice optical depths provided by the Emirates Exploration Imager (EXI) of the Emirate Mars Mission (EMM) will be used to investigate seasonal and diurnal variations of such clouds in the Tharsis volcanic region: Ascraeus Mons, Pavonis Mons, Arsia Mons, and Olympus Mons. Additionally, context will be provided using the meteorological fields from the Mars PCM (Mars Planetary Climate Model led by Laboratoire de Meteorologie Dynamique Paris, France). This study provides a general picture of how Martian water ice clouds correlate with Mars PCM's meteorological variables: water ice optical depth, atmospheric temperature, meteorological winds, and water vapor mixing ratio.