DUST REDISTRIBUTION ON MARS USING INTERANNUAL DIFFERENCES IN GLOBAL SURFACE TEMPERATURE

The present climate of Mars is punctuated by recurring regional-scale, and occasional global-scale, dust events, where dust is lifted from the surface and is transported by the atmosphere. Redistributed dust can brighten regolith, darken ices, and thermally insulate the surface due to its low thermal inertia. Widespread changes in albedo, associated with dust redistribution, are observed over multiple timescales. Of particular interest is the relationship to global dust storms, and whether their frequency is due to a limited, finite reservoir of surface dust. Theoretical climate models predict interannual changes in dust coverage before and after global storms, but vary substantially in the amounts and locations of transported dust. Changes in albedo or thermal properties will affect surface-energy balance, and therefore surface temperature. Here, using multi-year measurements of surface temperature and albedo from orbit, we can constrain interannual change in dust coverage and/or thickness globally. Visible datasets only provide a lower limit of dust added or removed due to the sensitivity of reflectance and small amount of dust (i.e., microns in thickness). Temperature data can be used to place an upper limit on changing dust thickness. This is because larger amounts of dust (100s of microns in thickness) must be added/removed to meaningfully affect insulating properties of the surface. This analysis of orbital data helps us understand global dust transport, the initiation of dust storms, and the overall climate of Amazonian Mars.