The terrestrial ice margin morphology in Kalaallit Nunaat (Greenland)

Abstract. The Greenland ice sheet (GrIS) and its peripheral glaciers and ice caps (PGIC) have received a lot of attention with respect to its marine-terminating, and considerably less for the remaining sections ending on land or in lakes. While the dominant part of ice mass imbalance is driven by calving at marine termini, a large part of the mass loss is caused by surface melt, leaving via those latter less studied margins. Relying on ice masks and a dataset for lake distribution we for the first time provide an assessment of the lengths of marine-, land- and lake-terminating margins across Greenland, showing that over a total length of 76154 km and 174425 km, for GrIS and PGIC respectively, 96.4 % (93.1 % and 97.8 %) of the margin is land-terminating, with the marine- and lake-terminating margin making up only 2.2 % (3.6 and 1.6 %) and 1.4 % (3.3 and 0.6 %). We also show that the ArcticDEM product is able to capture margin morphologies across large parts of the land-terminating margin, identifying 28.4 % as near-vertical features over shallow terrain, confirming earlier hypothesis of a large prevalence of these extremely steep features. 13.4 % are identified as steep (∼20–45°) and 17.3 % as shallow ramps (<20°). These data provide a basis to investigate the reason for surface morphology differences at terrestrial ice margins.