Convective Vortices and Dust Devils Detected and Characterized by Mars 2020
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS(2023)
摘要
We characterize vortex and dust devils (DDs) at Jezero from pressure and winds obtained with the Mars Environmental Dynamics Analyzer (MEDA) instrument on Mars 2020 over 415 Martian days (sols) (Ls = 6 degrees-213 degrees). Vortices are abundant (4.9 per sol with pressure drops > 0.5 Pa correcting from gaps in coverage) and they peak at noon. At least one in every five vortices carries dust, and 75% of all vortices with delta p > 2.0 Pa are dusty. Seasonal variability was small but DDs were abundant during a dust storm (Ls = 152 degrees-156 degrees). Vortices are more frequent and intense over terrains with lower thermal inertia favoring high daytime surface-to-air temperature gradients. We fit measurements of winds and pressure during DD encounters to models of vortices. We obtain vortex diameters that range from 5 to 135 m with a mean of 20 m, and from the frequency of close encounters we estimate a DD activity of 2.0-3.0 DDs km (-2) sol (-1). A comparison of MEDA observations with a Large Eddy Simulation of Jezero at Ls = 45 degrees produces a similar result. Three 100-m size DDs passed within 30 m of the rover from what we estimate that the activity of DDs with diameters > 100 m is 0.1 DDs km(-2)sol (-1), implying that dust lifting is dominated by the largest vortices in Jezero. At least one vortex had a central pressure drop of 9.0 Pa and internal winds of 25 ms (-1). The MEDA wind sensors were partially damaged during two DD encounters whose characteristics we elaborate in detail.
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关键词
Mars,dust sevils,Jezero,MEDA
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