Characterization of Ice Mélange and its Implications to Terminus Stability at Helheim Glacier, Southeast Greenland

Ice mélange, a conglomeration of icebergs and sea ice, persists in front of some marine-terminating glaciers. Depending upon local fjord geometry and other environmental conditions, an ice mélange can sometimes compact and jam. Here, the impact of the ice mélange on iceberg calving is assessed at a fast-moving glacier with a unique flow regime – Helheim Glacier, southeast Greenland (HG). Satellite remote sensing is used to quantify the ice mélange and the glacier terminus position, and additional ancillary data – wind speed, moorings, sea surface temperature (SST) and bed topography – are used to assess potential controls on iceberg calving. Iceberg jams were measured on a 2 to 35-day interval, but often did not correlate with the rate of calving. Isolated calving events were more likely during a jam, but most jams were in winter, when calving is most infrequent. At HG, SST and seasonality are the stronger drivers of iceberg calving