Effects of a Large Dust Storm in the Near-Surface Atmosphere as Measured by InSight in Elysium Planitia, Mars. Comparison With Contemporaneous Measurements by Mars Science Laboratory

摘要

NASA's InSight landed in Elysium Planitia (~4.5°N,136°E) at L_s ~ 296° (November 2018), right after the decay of the 2018 Global Dust Storm (GDS) and before the onset of the 2019 Large Dust Storm (LDS) at L_s ~ 320° (January 2019). InSight's cameras observed a rise in the atmospheric opacities during the storm from ~0.7 to ~1.9, similarly to contemporaneous measurements by Curiosity in Gale crater. Pressure tides were strongly affected at the locations of InSight and Curiosity. In particular, the diurnal pressure mode experienced an abrupt increase during the onset of the LDS, similar to that measured by Curiosity, most likely due to longitudinally asymmetric dust loading. Later, the dust was redistributed around the planet and the semidiurnal mode evolved according to dust opacity in both missions. Before and after the onset of the storm, the observed wind patterns resulted from the interaction between regional and local slope flows induced by topography, which all produced a diurnal perturbation superimposed on a mean flow, dominated by the Hadley cell but with modifications due to channeling effects from the regional topography. However, the onset of the LDS modified this to a scenario consistent with enhanced tidal flows. The local air temperatures are strongly perturbed by the lander's thermal effects, and their retrieval significantly depends on wind patterns, which changed during the course of the dust storm. Observations suggest a decrease in convective vortices during the dust storm; however, vortex activity remained strong during the storm's onset due to the increase in wind speeds.