Revisiting Trends in Greenland Ice Sheet Albedo Using the Combined MODIS and VIIRS Record

Abstract The MODerate resolution Imaging Spectroradiometer (MODIS) instruments onboard NASA's Aqua and Terra satellites have been used to monitor trends in Greenland Ice Sheet albedo for over two decades. These satellites, however, are nearing the end of their productive lifetimes meaning that continued investigation of ice sheet albedo trends will soon require a combination of MODIS and NOAA's Visible Infrared Imaging Radiometer Suite (VIIRS) products. Here we investigate the potential of multi‐sensor records for identifying broadband albedo trends on the Greenland Ice Sheet for the 2002−2024 period. We first use albedo measured by 33 automated weather stations on the ice sheet to show that the MODIS (MCD43A3) and two VIIRS (VNP43MA3 and VJ143MA3) surface albedo products have similar uncertainties. However, slight biases between MCD43A3 and VNP43MA3 cause a combined, multi‐sensor record to overestimate albedo trends in the accumulation zone and underestimate trends in the ablation zone, relative to a single‐sensor record. After describing these uncertainties, we extend the Greenland Ice Sheet albedo record back to 1941 using contemporary relationships between albedo, air temperature, and snowfall. Our reconstruction demonstrates that ice sheet albedo significantly declined across much of the ice sheet during the 1941−2024 period, especially in the ablation zone, primarily because of increasing air temperatures. Overall, our study characterizes uncertainties of the MCD43A3, VNP43MA3, and VJ143MA3 products and demonstrates the potential of both multi‐sensor harmonization and statistical reconstruction for extending Greenland Ice Sheet albedo records.