Variation in dune parameters with location and elevation in Titan's Belet Sand Sea highlight potential sediment transport patterns

Brad Bishop, Jani Radebaugh, Corbin Lewis
Brigham Young University, Provo, Utah, USA

Eolian dune fields found within the equatorial region of Saturn's moon Titan between +30 latitude cover approximately 15-17% of the surface. These dominantly linear dunes are similar in form, size, and radar reflectivity to the dunes of the Namib, Saharan, and Arabian deserts. Terrestrial dune patterns and their variation in width and spacing are the surface expressions of the inputs (sediment supply, winds, topography) controlling dune formation and dynamics. Applying these principles to analyses of linear dune patterns on Titan may elucidate surface-atmosphere interactions, to ultimately enable discovery of potential sediment transport patterns.

Within Titan's dune fields, initial studies of dune parameters utilizing a global approach have shown that dunes are generally wider at low latitudes (with an inflection point at 7 S). However, the evolution of dune width and spacing as material is transported in the migration direction (west to east) through a given sand sea system on Titan is not as well understood. Likewise, the relationship between dune width and spacing with regional topography is not well constrained. Using data gathered from the Cassini Synthetic Aperture Radar (SAR), we analyzed the morphometry of dunes across Belet, the largest sand sea on Titan. Using a new method developed in ArcMap 10.3 we produced approximately 8,800 new width and spacing measurements to investigate how the dunes evolve across the system. We also combined these data with a global topographic map to consider the effect of variations in elevation across Belet.

Results suggest that dune widths are smallest in Belet at ~13 N latitude and then gradually increase to be greatest at ~3 S latitude. Dune width and spacing correlate somewhat with longitude, decreasing in size to the east. An opposite trend for dune width might be expected for sand transport from west to east; dune width and spacing typically increase in the migration direction, where dunes originate at the upwind margin of a field. In Belet, a westward dipping regional slope may act to reverse the dune spatial trends. Characterizing these trends in relation to topography and distance from the upwind margin will help to constrain potential sediment transport patterns on Titan's surface.