Surface Dust Redistribution on Mars From Interannual Differences in Temperature and Albedo

摘要

The present climate of Mars is punctuated by recurring dust storm events, where dust is lifted from the surface and is transported by the atmosphere. Dust addition or removal can brighten or darken the surface, as well as affect thermal insulating properties because of its low thermal conductivity. Of particular interest is the recurrence of global dust storms (GDSs) and whether their frequency is controlled by the replenishment or depletion of finite surface reservoirs between events. Global climate models predict changes in dust coverage before and after global storms, but output varies substantially regarding the amounts and locations of transported dust. The analysis of global, multiyear observations of surface temperature and albedo from orbit can constrain changes in dust coverage and/or thickness. We calculate and map interannual differences in surface temperature from Mars Year (MY) 24 through MY35 to identify regions of dust redistribution. Regional temperature changes across the MY25 GDS can be explained by changes in albedo and do not require changes in surface thermal properties, supporting extremely small dust thickness changes. Across the MY34 GDS, we find less extensive changes in surface temperature, indicating a reduced impact on dust redistribution compared to MY25. However, we identify a region between Acidalia and Arabia Terra that experienced substantial dust removal and positively correlates with visible high-resolution orbital images. Our work supports minuscule changes in dust thickness from the observed GDSs and is consistent with effectively infinite dust reservoirs on timescales of at least 10 3 years.