Snow and regolith albedo variations using CRISM data at McMurdo crater, Mars

The cryosphere component provides the most reliable and insightful indications of any planet’s climate dynamics. Using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), we develop a novel approach to determining the broadband Visible and Near Infrared (VNIR) albedo of the Martian surface. This study focuses on albedo changes in the McMurdo crater, part of Mars’s south polar layer deposits. We compare seasonal and interannual variations of the McMurdo surface albedo before, during, and after the Global Dust Storm (GDS) of Martian Year (MY) 34. As the seasons progressed from spring to summer, the mean albedo in MY 32 and 34 plunged by over 40%, by about 35% in MY 33, and by slightly more than 30% in MY 35. Compared interannually, however, mean albedo values within both seasons (spring and summer) exhibited no significant differences in those same years. Notably, interannual albedo difference maps reveal albedo variation of more than ±0.3 in certain regions of the crater. Considering only snow-covered pixels, interannual albedo differences suggest that Mars dust had a pervasive impact on Mars’s cryosphere. Variations in maximum and minimum albedo values as high as 0.5 were observed, depending upon differences in the dust levels in Martian snow/ice. The maximum and the minimum snow albedo values were lowest in MY 34, indicating the effect of the intense dust storm event that year. The average snow albedo decreased from 0.45 in MY 32 to 0.40 in MY 33 and to 0.33 in MY 34, and then rose back to 0.40 in MY 35. This trajectory suggests a temporary deposition of dust, partially reversed after the GDS by self-cleaning mechanisms (local aeolian process and CO₂ sublimation/deposition cycle).