Abstract:

Mass loss of the Greenland ice sheet has accelerated in recent years due to increases in surface meltwater runoff. Each year during the melt season, large and complex supraglacial river networks form on the northwest Greenland ice sheet surface. A large amount of meltwater is transferred to the ice sheet margin, feeds the proglacial river network and finally flows into the ocean. This process is important, because it considerably affects ice sheet mass balance and contributes to global sea rise. However, there have been few studies investigating the proglacial and supraglacial river network of the northwest Greenland ice sheet and the morphological and structural characteristics remain unclear. Here, we extracted the supraglacial and proglacial river network in the Inglefield Land(4 624 km²) from 10 m Sentinel-2 images acquired on July 25, 2018, August 14, 2018 and August 25, 2018 using the criteria of Gaussian-like backscattering cross sections and longitudinal continuity. We monitored the dynamic changes of supraglacial and proglacial river network by supraglacial drainage density and proglacial river width. We found that there are parallel supraglacial drainage patterns and dendritic proglacial drainage patterns on the northwest Greenland ice sheet during the melt season, and supraglacial river networks are gradually expanding toward higher elevation. We found a high level of consistency between proglacial river width and supraglacial drainage density.

Key words: supraglacial river network, proglacial river network, drainage density, ice surface melt, Greenland ice sheet