Titan as a Laboratory for Linear Dune Formation

Introduction: Synthetic Aperture Radar images of Titan collected by the Cassini spacecraft show that dunes are abundant on Titan's surface, covering almost 20% of Titan's surface [1,2]. Nearly all of the dunes found on Titan are linear in form, are found near the equator (±30and have a west-east orientation. Since there is likely active linear dune formation presently on Titan [3], we can use Titan as a laboratory to study atmospheric conditions and dune processes of a younger Earth. Titan not only has active winds and a supply of dune-forming organic sediments , but where dunes form there are no large bodies of liquids, vegetation, or large topographic obstructions to disrupt global wind patterns or dune formation [1,2]. There are multiple variables that control linear dune formation, both on Earth and on Titan, including sediment supply, wind regime, basin location and dune induration (solidification) due to moisture. We present the results of a detailed morphological study of select dune fields on Titan, un-dertaken in order to explore possible linear dune controls on Titan and on Earth. Problem: Dune fields on Titan are sufficiently abundant that they represent the results of major atmospheric and surface processes on Titan. Thus, a detailed analysis of these features will illuminate important relationships and processes. Large-scale dune orientation surveys [4] feed directly into global models for atmospheric transport and wind. Detailed studies on a discrete sand sea region (covering several hundred square kilometers on Titan) provide information on small-scale wind transport, wind interactions with topography, and variations with latitude , related to climate differences on Titan. In addition to furthering our understanding of Ti-tan, studies of dune processes on Titan will apply directly to our understanding of dunes on Earth. Linear dunes are the most common desert dune form on Earth, accounting for up to 40% of Earth's desert dune forms [5] and usually occurring in extensive dune fields. Despite their abundance, the processes that form them are not well understood. Since dunes cover such a large part of the Earth's and Titan's surfaces (up to 10% and 20% of the total land surface respectively) and form part of the sediment transport system, an understanding of dune processes contributes directly to an understanding of sediment concentration , transport and wind-surface interactions [6]. Many of the linear dunes we observe on Earth were