Surface Dust Redistribution on Mars From Interannual Differences in Temperature and Albedo. Issue 12 (24th December 2022)

• Record Type: Journal Article
• Authors: Bapst, J.; Piqueux, S.; Edwards, C. S.; Wolfe, C.; Hayne, P. O.; Kass, D. M.; Kleinböhl, A.
• Is Part Of: Journal of geophysical research. Volume 127:Issue 12(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-12-24
• Subjects: Mars -- dust -- thermal infrared -- albedo -- surface -- storm; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1029/2022JE007365
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: 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. Plain Language Summary: Storm activity on Mars can mobilize surface deposits of fine dust and redistribute that dust across the surface. It is not known whether surface dust must be replenished or removed in specific geographic regions as a condition for the largest, global‐scale storms to initiate. Surface dust deposition and removal can affect both the reflectivity and the physical properties of the surface. Fine‐grained dust is more reflective than the typical Martian surface and large quantities of dust can thermally insulate the surface like a blanket. Both effects will impact the surface temperature. By mapping year‐to‐year changes in surface temperature from orbital observations, we identify regions where dust has been deposited or removed. The largest changes result from global‐scale dust storms that can last weeks. The observations support very small changes in dust thickness across the surface (less than the width of a human hair), where dust is only affecting the reflectivity of the surface. Analysis of observations spanning 10 Mars years (almost 20 Earth years) captures two global storms with vastly different propensities for dust redistribution. We argue that dust reservoirs (sources) can supply a global dust storm in any given Mars year. Key Points: Interannual surface temperature changes observed about the Mars Year (MY) 25 global dust storm (GDS) are explained fully by surface albedo changes due to dust redistribution Small dust thickness changes about GDS and meter‐thick reservoirs imply quasi‐infinite dust availability on the order of ∼1, 000 years or more Interannual temperature changes observed about the MY34 GDS are corroborated by visible images showing clear evidence of dust removal