Description of Martian Convective Vortices Observed by InSight and Implications for Vertical Vortex Structure and Subsurface Physical Properties

Convective vortices (whirlwinds) and dust devils (dust-loaded vortices) are one of the most common phenomena on Mars. They reflect the local thermodynamical structure of the atmosphere and are the driving force of the dust cycle. Additionally, they cause an elastic ground deformation, which is useful for retrieving the subsurface rigidity. Therefore, investigating convective vortices with the right instrumentation can lead to a better understanding of the Martian atmospheric structures as well as the subsurface physical properties. In this study, we quantitatively characterized the convective vortices detected by NASA's InSight (similar to 13,000 events) using meteorological (e.g., pressure, wind speed, temperature) and seismic data. The evaluated parameters, such as the signal-to-noise ratio, event duration, asymmetricity of pressure drop profiles, and cross-correlation between seismic and pressure signals, are compiled as a catalog. Using these parameters, we investigated (a) the vortex structure and (b) the subsurface physical properties. Regarding the first topic, we tried to illustrate the vertical vortex structure and its link to the shape of the pressure profiles by combining the asymmetrical features seen in the observed pressure drops and the terrestrial observations of dust devils. Our results indicate that most of the vortices move with the wall tilted in the advection direction. Concerning the second topic, selecting the highly correlated events between pressure perturbation and ground response, we estimated the subsurface rigidity at the InSight landing site down to 100 m depth. Our results indicate that the subsurface structure can be modeled with two layers having a transition at 5-15 m depth. Plain Language Summary As frequently observed on Earth, convective vortices or dust-loaded vortices are also seen on Mars. They reflect the local atmospheric structure and are the main driving force to lift the fine dust from the ground. In 2018, NASA's InSight succeeded in installing the meteorological and geophysical packages on Mars. That brought us, in particular, meteorological data with an extremely high temporal resolution, contributing to resolving local phenomena such as convective vortices. In this study, using InSight's meteorological (e.g., pressure, air temperature) and seismic data, we quantitatively characterize convective vortices to understand this phenomenon from both meteorological and geophysical aspects. Especially focusing on the asymmetricity of pressure drop profiles at vortex encounters and the correlation between the pressure variations and seismic signals, we investigated (a) a link between the shape of pressure drop profiles and the vertical vortex structure and (b) the ground rigidity structure by measuring the ground responses against the vortex-related pressure variations. Consequently, first, we found that most of the vortices move with the wall tilted in the advection direction. Second, our results indicated that the subsurface structure can be modeled with two layers down to 100 m with a transition at 5-15 m depth.