REGIONAL ANALYSES OF TRANSVERSE AEOLIAN RIDGES ON MARS: ORIENTATION, MORPHOLOGY, AND MORPHOMETRY

Transverse Aeolian Ridges (TARs) are bright (high albedo), decameter-scale bedforms with apparent ‘ripple-like’ morphologies formed normal to wind direction and found throughout the equatorial and mid-latitudes on Mars. For this study, analyses of TAR orientation, morphology, and morphometry were performed on high-resolution images across a variety of geographic locations providing regional case studies for the examination of TAR behavior/characteristics as indicators of recent aeolian processes in Martian history.

Using ArcGIS software to manage data from the ConTeXt Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) camera aboard the Mars Reconnaissance Orbiter (MRO) spacecraft, TARs within six previously mapped study areas were categorized in terms of orientation and morphology. Analysis of TAR orientations shows a predominantly N-S orientation in four of the six study areas—those in the mid-southern and equatorial latitudes—while TARS within the mid-northern latitudes adopt W-E and NW-SE orientations. These trends suggest that TAR formation is driven primarily by large-scale winds, and are consistent with results from General Circulation Models. Additionally, TARs were assigned a morphological designation based on plan-view crest structure: simple, sinuous, forked, networked, or barchan-like. TAR morphology across five of the six regions is overwhelmingly classified as simple accounting for 183,825 km² of the 268,650 km² of total TAR coverage (68%).

Digital Terrain Models (DTMs) created from stereo pairs of overlapping HiRISE images were used to draw topographic profiles, enabling cross-section analysis of TAR morphometry for 1,509 total bedforms. These measurements indicate that TARs within the study regions are small (1.32 m high on average), extremely symmetrical, with wavelengths averaging 10-50m and ripple indexes ranging from 30-40. Comparison of TAR profiles with those of terrestrial analogs place TARs within the bounds of large megaripples and small reversing dunes.

Quantifying the characteristics of TAR shape, size, and orientation within segregated study regions provides localized data for assessing regional controls on the formation of TARs.