Mixing time scales of dustiness and some associated effects at middle atmosphere during the 2018 global dust storm

This study analyzes some characteristic features associated with the Mars year 34 (2018) global dust storm (GD18) using the retrievals of Mars Climate Sounder (MCS) and Mars Color Imager (MARCI) onboard Mars Reconnaissance Orbiter (MRO). According to the MRO MARCI's weather report and Mars daily global maps, the GD18 resulted from a large precursor dust storm in the broader Acidalia region at L-S similar to 186 degrees and developed into a global scale storm at L-S similar to 194 degrees. Dust lifting is reported to continue until L-S similar to 207 degrees in MARCI images, and the MCS-derived column dust opacity peaks around L-S 208 degrees. However, the middle atmospheric dust loading only peaks around L-S 211 degrees, i.e., 3-4 degrees LS after the surface dust lifting maximum. High-altitude dust maximum is evident after L-S similar to 190 degrees, a few degrees of L-S after the large precursor Acidalia dust storm. These delays probably indicate a vertical mixing timescale similar to that for a regional scale storm, indicating a common mechanism irrespective of the spatial scale of a dust storm. During GD18, the diurnal tide is strongly amplified at high altitudes, away from the tropics (especially over SH), and the vertical extent of clouds is significantly reduced. These changes are consistent with the time scale of the evolving vertical distribution of dust observed by MCS. (C) 2021 COSPAR. Published by Elsevier B.V. All rights reserved.

Automated summary

This study analyzes characteristic features of the Mars year 34 (2018) global dust storm (GD18) and finds specific temporal and spatial characteristics in the formation and propagation of the storm. It is observed that the vertical mixing timescale is independent of the spatial scale of the dust storm.