A decade of summer glacier fronts and calved glacier ice distribution in Kongs- and Krossfjorden, Svalbard, observed by Sentinel-1 extra wide swath

A statistical method to map atmospheric exposure is applied on the whole decade (2015–2024) of Sentinel-1 summer acquisitions in Extra Wide Swath mode over Kongs- and Krossfjorden on Svalbard. The consistent daily observations not only allow to statistically define a summer glacier front extent of marine-terminating glaciers but also reveal a new application, which is to detect the summer distribution of calved glacier ice, i.e. icebergs, bergy bits and growlers (IBG). These originate from glacier calving during the sea-ice free period. Summer glacier extent that we define statistically as the area where the glacier prevails more than 95% during summer co-locate well with independent glacier fronts digitized from Sentinel-2 optical imagery. Annual summer IBG distributions are classified into percentage ranges of temporal occurrence, representing the proportion of time IBG are detected in the corresponding pixel location. The ten-year record of mean annual summer IBG-occupied areas is compared to separate estimates of summer glacier frontal ablation for the two glaciers Lillehöökbreen and Kronebreen. The comparison indicates a clear link between mean summer calved ice distribution area and the glaciers' frontal ablation with correlation coefficients (r) of 0.67 and 0.85 for Lillehöökbreen and Kronebreen, respectively. Frontal ablation includes both calving and submarine/subaerial melting at the glacier front and combining this with IBG occurrence estimates may provide new insights into the mass loss ratio between calving and melting. However, the relationship between IBG occurrence distribution and frontal ablation appears to be glacier specific. As this study represents a first attempt to map IBG occurrence distribution and mean IBG occupied area and link that to glacier frontal ablation, further studies and application on other glaciers and fjord systems are required to fully assess the potential and limitations of mapping such IBG distribution as a proxy for glacier calving intensities.