Bathymetry data reveal glaciers vulnerable to ice‐ocean interaction in Uummannaq and Vaigat glacial fjords, west Greenland

• Published in: Geophysical research letters Vol. 43; no. 6; pp. 2667 - 2674
• Main Authors: Rignot, E., Fenty, I., Xu, Y., Cai, C., Velicogna, I., Cofaigh, C. Ó, Dowdeswell, J. A., Weinrebe, W., Catania, G., Duncan, D.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28-03-2016
• Subjects: Bathymetry; Brackish; Charts; Climate Change; Continental shelves; Data; Echo sounding; Echoes; Echosounding; Erosion; Evolution; Fjords; Fronts; Glacial erosion; Glaciation; Glacier fronts; Glaciers; Glaciology; Greenland; Ice; Ice‐Ocean interaction; Marine; Mass; Mass balance of ice sheets; Melts; Ocean floor; Oceanography; Oceans; Shallow water; Sills; Sounding; Surveying; Valleys; Greenland; ANW, Greenland, Vestgroenland, Uummannaq; PN, Greenland, Greenland Ice Sheet; ANW, Greenland, Vestgroenland, Vaigat; AN, Greenland
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2016GL067832

Marine‐terminating glaciers play a critical role in controlling Greenland's ice sheet mass balance. Their frontal margins interact vigorously with the ocean, but our understanding of this interaction is limited, in part, by a lack of bathymetry data. Here we present a multibeam echo sounding survey of 14 glacial fjords in the Uummannaq and Vaigat fjords, west Greenland, which extends from the continental shelf to the glacier fronts. The data reveal valleys with shallow sills, overdeepenings (>1300 m) from glacial erosion, and seafloor depths 100–1000 m deeper than in existing charts. Where fjords are deep enough, we detect the pervasive presence of warm, salty Atlantic Water (AW) (>2.5°C) with high melt potential, but we also find numerous glaciers grounded on shallow (<200 m) sills, standing in cold (<1°C) waters in otherwise deep fjords, i.e., with reduced melt potential. Bathymetric observations extending to the glacier fronts are critical to understand the glacier evolution.
Key Points
Bathymetry mapping extending to ice fronts essential in Greenland fjords
Fjords are far deeper than expected and host warm, salty waters where deep enough
Many glaciers are retreated in shallow waters in otherwise deep fjords