Multidirectional Dune Dynamics Under Seasonal Winds on Mars

Abstract

We present a systematic assessment of the complex aeolian bedforms across the western rim of Hellas Planitia, the largest impact basin on Mars. Repeat orbital imaging shows crescentic, transverse, and star dunes across the Hellespontus Montes region migrate, converge, and occasionally reverse course. Dune morphology and sand ripple migration identify three effective wind regimes that vary spatially and temporally, correlating with atmospheric modeling. Peak sand transport occurs during southern spring and summer to the west and southwest, driven by daytime anabatic slope winds originating from Hellas. Migration rates decline with waning temperatures, when eastward drainage winds into Hellas dominate nights annually and during the colder seasons. However, these diurnally and seasonally cyclic slope winds can be highly localized, as nearby barchan fields swiftly migrate exclusively west where eastward winds are mitigated by topography. These novel findings highlight the complexity of surface-atmosphere interactions in shaping aeolian systems on Mars.