Characterization of ice features in the southwest Greenland ablation zone using multi-modal SAR data

Abstract. This study investigates ice features of unknown glaciological origin in the ablation zone of southwest Greenland, focusing on the land-terminating Russell Glacier. Using data from an experimental airborne SAR (Synthetic Aperture Radar) campaign of the German Aerospace Center (DLR), the research employs a range of advanced techniques, including SAR polarimetry, interferometry, tomography, and modeling, to characterize these features. The analysis reveals that in low-backscatter areas, surface scattering is dominant with no correlation to topography or surface characteristics. In contrast, surrounding high-backscatter areas are characterized by volume scattering and the presence of subsurface scattering structures. A significant aspect of this study involves comparing the observed ice features with known glaciological phenomena in the ablation zone. However, the combined findings, along with the temporal stability of these features, as seen through annual SAR backscatter analysis, complicate a straightforward glaciological explanation. A first theory involves the presence of a weathering crust causing these low-backscatter features due to residual liquid water content. These findings could improve our understanding of surface and subsurface processes in the ablation zone, contributing to better mass balance assessments.