Presentation #332.06 in the session The Sun and Solar System II.
An important and perhaps dominant source of dust in the martian atmosphere, dust devils play a key role in Mars’ climate. Datasets from previous landed missions have revealed dust devil activity, constrained their structures, and elucidated their dust-lifting capacities. However, each landing site and observational season exhibits unique meteorological properties that shape dust devil activity and help illuminate their dependence on ambient conditions. The recent release of data from the Mars Environmental Dynamics Analyzer (MEDA) instrument suite onboard the Mars 2020 Perseverance rover promises a new treasure-trove for dust devil studies. In this study, we sift the time-series from MEDA’s Pressure Sensor (PS), Radiative and Dust Sensors (RDS), and Atmospheric Temperature Sensors (ATS) to look for the signals of passing vortices and dust devils. We detected 309 vortex encounters over the mission’s first 89 sols and 510 during the next 89 sols. Consistent with predictions, these encounter rates exceed InSight and Curiosity’s encounter rates. The RDS time-series also allows us to assess whether a passing vortex is likely to be dusty (and therefore is a true dust devil) or dustless. We find that about one quarter of vortices show signs of dust-lofting, although unfavorable encounter geometries may have prevented us from detecting dust for other vortices. In addition, we analyzed the ATS time-series data corresponding to vortex encounters, and by combining the vortex pressure and temperature excursions, we are able to estimate the height of the convective vortices. Consistent with expectations for the diurnal growth of the planetary boundary layer, their heights reach a maximum toward mid-day, with a steady decline before and after.