Intra-annual evolution of ponded crevasses across the Greenland Ice Sheet

Ponded crevasses on the Greenland Ice Sheet impact the retention and drainage of surface meltwater in the low elevation zone and enhance the melt of ice sheet. However, current understanding is limited to a few glaciers, leaving their inter- and intra-annual evolution largely unknown at an ice-sheet-wide scale. This study presents an automated methodology to map ponded crevasses from 10-m resolution Sentinel-2 satellite images to produce the first pan-Greenland dataset describing their intra-annual evolution during the warm 2019 melt season. The results indicate that: 1) the central-western and southwestern basins exhibit earlier drainage onsets, due to the high surface meltwater runoff in the early melt season; 2) local topographic depressions favor higher areal expansion and shrinking rates of ponded crevasses; 3) towards the end of the melt season, a considerable amount of ponded crevasse area remains (~10% relative to the peak), suggesting the possible retention. We will further apply the proposed method to the Sentinel-2 images from 2016 to 2025 to reveal how the intra-annual evolution of ponded crevasses responds to varying climatological settings.