Identifying the Role of Clouds in the Recent Decrease in Top of the Atmosphere Reflectance Over Greenland

In the period of Arctic Amplification, with surface temperatures at high northern latitudes rising faster than those at the mid-latitudes, the Arctic is undergoing significant changes. Among these changes are the retreat of sea ice and the melting of glaciers, processes that affect the spectral reflectance of solar radiation at the surface. By detecting subtle changes in reflectance at the top of the atmosphere (RTOA) as measured by the GOME-2 scanning spectrometer, we have identified significant negative trend (at 95% confidence) over the Greenland ice sheet (GrIS) for the period 2007-2024. We analyze the causes behind this RTOA drop through a combination of the AVHRR-based CLARA-A3 CM SAF’s Cloud, Radiation and Surface Albedo data record, ECMWF Reanalysis v5 (ERA5), and ground based measurements from Summit Station, Greenland. The primary focus of this combined spatiotemporal analysis is to better understand the impact of clouds on RTOA as well as on the surface conditions over the GrIS. Moreover, we aim to deduce how the atmospheric conditions over Greenland are responding to a warming Arctic climate system and what that means for GrIS in the years to come. At EGU25, we will present our most recent findings from our multi-dataset study and share our conclusions on the role of clouds in the observed drop in RTOA above Greenland.

This research is supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the Transregional Collaborative Research Center TRR 172 “ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)³.