302-9 Snow vs. Sand: Sand Dune Thermal Profiles in Kobuk Valley, Alaska, and Implications for Planetary Dunes

Session: Aeolian Systems in Time and Space (Posters)

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The Great Kobuk Sand Dune field of Kobuk Valley, Alaska, may provide valuable insight into eolian processes in cold environments across our Solar System, such as on Mars and Titan. The ARRAKIS project (Assessing Regional Reflectors of Astrobiology in Kobuk Dunes for Interplanetary Science), part of the NASA PSTAR (Planetary Science and Technology for Analog Research) grant program, seeks to understand what technology can reveal about cold-climate surface and subsurface sand dune properties, in particular their moisture distribution and astrobiological potential.

Work performed during a March 2025 field season examined the thermal response to sunlight of a snow-covered, N-S oriented transverse dune. We obtained visible and thermal images hourly from 7:30 to 21:30 using a DJI Mavic 3T drone, which has infrared (IR) imaging capability at wavelengths of 8 to 14 micrometers. Snowmobile tracks visible in many images serve as fiducials and reveal the contrast between compacted vs untouched snow. In the early morning, the snow track is warmer than the surrounding snow but has reduced temperature contrast during midday. The compacted snow has a higher density and therefore higher thermal inertia. Other small-scale features may be the result of differing snow densities and are most apparent during early morning hours, when solar reflection is minimal. At 14:30, solar noon, solar reflection is at a maximum and no areas of the image are in shadow, so all thermal contrasts are a result of snow density differences and possible differences in albedo. On the lee slope of the dune, some especially bright (i.e., hot) and dark (i.e., cold) spots are seen in IR along the main dune crest. These anomalies are of particular interest because they influence where thermal energy is most intense on the dune’s lee slope. Most other observed differences in image brightness are a result of dune topography and shadowing.

Our study results could be applied to Martian frost-covered dunes and the response to solar illumination as observed by instruments such as Mars Odyssey’s THEMIS. Where thermal energy is most intense on a dune slope could affect where liquid water resides in the dune, which is important for astrobiology. Preliminary results of upcoming September 2025 thermal observations of bare dune sand will also be discussed.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10145

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