Dust Devil Optical Depth Change Calculations Using MSL REMS UV Sensor Data

Abstract

We use data from the rover environmental monitoring station Ultraviolet (UV) sensors onboard the Mars Science Laboratory Curiosity rover to retrieve changes in optical depth for the passing vortices that have simultaneous drops in pressure and UV irradiance. Retrieved vortex optical depths are relatively small, falling mostly below 0.1. Exceptions include seasonal and diurnal patterns of elevated lifting above 0.1, with a maximum observed between 0.35 and 0.4. The highest changes in optical depths are observed just after Vera Rubin ridge and within Glen Torridon. The seasonal trends in vortex optical depth are generally correlated with the overall optical depths derived from Mastcam 880 nm observations, except in the dusty season, which also exhibits an anti‐correlation to frequency and mean retrieved optical depth change. This suggests it does not take an appreciable amount of total atmospheric aerosol loading to reduce convective activity. No strong correlation is observed between the measured pressure depths and the retrieved vortex optical depths. While there are seasonal trends in the magnitudes of UV drops over the course of the mission, larger magnitudes tend to occur near sandier patches within any given season.