Semiautomated Identification and Characterization of Dunes at Hargraves Crater, Mars

Abstract

The Mars Global Digital Dune Database (MGD(3)) contains information on Martian dune fields and prepared manually from the Thermal Emission Imaging System (THEMIS; 100 m/pixel) images. Although the MGD(3)outlines dune fields, it overlooks the recognition of smaller dune forms. This paper aims to identify individual dunes from a semiautomated object-based image analysis technique and characterize dune materials at Hargraves crater, Mars. MGD(3)would benefit to be updated for an improved understanding of the Martian surface and its atmospheric mechanisms at a local scale. An object-based image analysis technique was applied here to the Context Camera (CTX; 6 m/pixel) data set to extract dune data in a more efficient, reliable, and accurate fashion. This study is a test case in validating a remote sensing method that has wide applicability to the entire Martian surface resulting in an update to the dune database at a higher spatial resolution-providing a better understanding of surface and atmospheric behavior of Mars at the local scale. We also explored the wind flow and dune stability-presenting an insight into the dune modification mechanism-within the crater. The prevailing wind inside the crater flows to the west-northwest. The dunes are labeled as active (stability index of 2) and do not appear to have been influenced by subsurface water ice or volatiles. We emphasize that the technique used here has a wide prospect in temporal monitoring of dune sediment flux, dune migration or erosion rates, improving near-surface airflow modeling, and dune stability analysis. Plain Language Summary The Mars Global Digital Dune Database (MGD3) contains morphologic information on Martian dune fields. MGD3 has various science applications including atmospheric circulation modeling, planetary climate change, mechanical weathering processes, and future rover lander missions to Mars. However, the database was prepared manually through visual photointerpretation from low-resolution satellite images of 100 m/pixel and, consequently, overlooked the recognition of smaller dune forms. Thus, MGD3 would benefit to be updated for an improved understanding of the Martian surface and its atmospheric mechanisms including near-surface wind patterns at a local scale as opposed to the global scale. We used a semiautomated object-based image analysis (OBIA) technique from higher-resolution images of similar to 6 m/pixel-more than 10 times higher spatial resolution compared to the previous imagery. Using the technique, we extracted individual dunes at Hargraves crater in a more efficient, reliable, and accurate fashion. The validated and accurate result in this study indicates the applicability of the OBIA method for the entire surface of Mars. Thus, the application OBIA method will be a great improvement for futures studies on Martian (and terrestrial) dune fields including temporal monitoring with better estimates of sediment flux, dune migration or erosion rates, and improving near-surface airflow modeling.