LINEAR DUNES IN THE WESTERN SAHARA AS AN ANALOGUE TO DUNES ON TITAN

Tens of thousands of sand dunes encircle the equatorial latitudes of Saturn’s moon Titan, as seen by the Cassini Radar SAR and visible-NIR instruments. These are linear in form, comparable in size and morphology to large linear dunes in the Namib and Western Egyptian desert (or occidental Sahara). Titan’s dunes do not appear to have overlapping or large flanking dunes, visible at Cassini SAR resolutions, that are typical of Earth’s big, complex linear dunes and result from changing wind regimes over thousands of years. Thus, Titan’s dunes may be highly evolved by terrestrial standards, present in the current wind regime long enough to allow organization of sands into single, large dune forms. Studies of linear dunes in the eastern Sahara desert provide field comparisons for Titan’s dunes. GPS traces of dune summits indicate winds draw dune sands into broad plinths with steep summits that shift with recent winds. The summits of the Qattameya Dunes west of Cairo are drawn out into crescents along the dune long axis from dominant, northerly winds on a NNW-trending crestline. A GPR survey shows equal spacing in the dune sedimentation, suggesting continuous, regular winds. Morphological, OSL, and GPR studies of Egyptian dunes will help us determine the long-term effects of wind trends on migration, sedimentation patterns, and change in form. These analyses can be related to studies of wind pattern effects on Titan’s dune forms, residence time of sands within dunes on Titan, and the creation and maintenance of evolved dune forms across Titan.