Dynamical phenomena in the atmosphere of Mars imaged with the Visual Monitoring Camera onboard Mars Express

The Visual Monitoring Camera on board Mars Express provides images of varied resolutions, covering a wide range of locations and seasons, and has been taking images for several Martian years. This large image database can be exploited to study various dynamical phenomena, and in this work, we concentrate on the study of cloud and dust storm activity in the polar regions, describing vortices, cloud evolution, and regional dust storms as well as the presence of gravity waves. Tracking the motions of details in the images, we estimate local winds, compare our results with predictions from the Mars Climate Database in different scenari, and study their seasonal evolution and potential inter annual variability. Further, resolution of images captured near pericenter is sufficient to allow the detection of gravity waves in the troposphere, identified as regular patterns in the cloud fields. We measure some of the basic properties of these waves, such as horizontal wave vector and extension of wave trains. We analyse those properties in relation to their aerographic location, local time and season, in the context of a recent study of the distribution of gravity waves on the lower atmosphere of Mars as inferred from the analysis of temperature fields by the Mars Climate Sounder onboard the Mars Reconnaissance Orbiter (MRO) (Heavens et al. ICARUS 2020).