Mars global digital dune database and initial science results

A new Mars Global Digital Dune Database (MGD(3)) constructed using Thermal Emission Imaging System (THEMIS) infrared (IR) images provides a comprehensive and quantitative view of the geographic distribution of moderate- to large-size dune fields ( area > 1 km 2) that will help researchers to understand global climatic and sedimentary processes that have shaped the surface of Mars. MGD(3) extends from 65 degrees N to 65 degrees S latitude and includes similar to 550 dune fields, covering similar to 70,000 km(2), with an estimated total volume of similar to 3,600 km(3). This area, when combined with polar dune estimates, suggests moderate- to large-size dune field coverage on Mars may total similar to 800,000 km(2), similar to 6 times less than the total areal estimate of similar to 5,000,000 km(2) for terrestrial dunes. Where availability and quality of THEMIS visible (VIS) or Mars Orbiter Camera narrow-angle (MOC NA) images allow, we classify dunes and include dune slipface measurements, which are derived from gross dune morphology and represent the prevailing wind direction at the last time of significant dune modification. For dunes located within craters, the azimuth from crater centroid to dune field centroid (referred to as dune centroid azimuth) is calculated and can provide an accurate method for tracking dune migration within smooth-floored craters. These indicators of wind direction are compared to output from a general circulation model (GCM). Dune centroid azimuth values generally correlate to regional wind patterns. Slipface orientations are less well correlated, suggesting that local topographic effects may play a larger role in dune orientation than regional winds.