CLIMATE-DRIVEN EROSION PATTERNS IN SOUTHERN HEMISPHERE DUNE FIELDS ON MARS

Studies of recent climate change on Mars have sought to determine the magnitude and frequency of climate changes by studying their impact on geological and atmospheric processes. Sand dunes and other aeolian features are unique in the study of climate change in that they are geological features formed by atmospheric forces. In particular, cold-climate sand dunes are surface features that become more active under windy, nonicy conditions, but less active under nonwindy and/or icy conditions. Thus they are extremely sensitive to changes in temperature, humidity, and atmospheric dynamics that drive climate change. The presence of a well-defined shift in southern hemisphere dune morphology may shed new light on recent climate change on Mars. Poleward of roughly 60°S, dunes take on a rounded and eroded appearance consistent with inactivity, whereas dunes equatorward of this latitude appear largely indistinguishable from active dunes.

All dune fields poleward of 55°S that are visible in Mars Odyssey THEMIS visible images and Mars Global Surveyor Mars Orbiter Camera (MGS MOC) images have been identified and categorized according to their level of degradation. Preliminary results suggest that the morphological shift occurs at approximately 60°S at all longitudes, generally corresponding well with the boundary of near-surface ground ice according to ground ice models, terrain morphological studies, and data from the Neutron Spectrometer on Mars Odyssey. In one meridional corridor (40°E-130°E, south and east of Hellas Planitia), Neutron Spectrometer data extend as far north as 50°S. This bulge is not reflected in dune morphology, suggesting that any link between ground ice and dune morphology is complex.