Presentation #113.02 in the session Martian Atmospheric Models, Local to Global.
The Mars Environmental Dynamics Analyzer (MEDA) on the Mars 2020 Perseverance rover includes novel sensors that detect dust clouds and dust devils via changes to direct and scattered sunlight, as well as changes to surface albedo indicating dust removal, all at 1Hz frequency and simultaneous with measurements of pressure, temperatures at multiple heights, wind, and relative humidity. The SuperCam and EDL microphones are the first to operate on Mars and provide data on turbulence, vortices, and wind activity, and the Navcam and Mastcam-Z cameras provide imaging of aeolian features and activity, including dust devils and gust-driven lifting. Jezero crater contains many aeolian surface features and hundreds of examples of aeolian activity have been observed over the first 500 sols of the mission (covering early spring through winter solstice), including active dust lifting during an early regional dust storm. While the data alone provide great insight, we show how atmospheric modeling at a variety of scales provides a means of forming and testing hypotheses about atmospheric and aeolian processes on Mars, and placing data into a regional/global context. The MarsWRF model, run as a global model with “nested” mesoscale domains at grid spacings down to ~1.4 km, captures the influence of global, regional, and local scale circulations. In combination, model and observations suggest that regional-scale upslope flows dominate the daytime circulation and are only slightly modulated by the local crater topography, whereas at night the circulation is dominated by local topography and modulated by regional flows. Daytime fluctuations in winds and rare but intense ‘gust lifting’ events are interpreted as large-scale convection cells with strong gust fronts being advected across the crater, with the estimated dimensions and dust lifting patterns consistent with cells found in the above simulation as well as in MarsWRF large eddy simulations (LES) run at 10m grid spacing. The orientation of wind tails observed along the rover traverse are determined to be consistent with present day sand fluxes, estimated both from extant wind data and from a full year of MarsWRF simulated wind stresses. However, the orientation of ventifacts is not consistent with present day winds, and modeling is used to assess the likelihood of a past climate scenario, including testing the impact on results of variations in orbital settings or local topography. Finally, the LES is used to estimate the rates of dust lifting by vortices and gust fronts assuming different thresholds for dust lifting, which are compared to those estimated from Mars 2020 data.