Mapping the spatial variations of the hydrographic properties of warm subtropical-origin waters penetrating the previously unmapped glacial fjords of Northwest Greenland

Abstract:

Motivated by the widely-recognized need to understand the possible connection between the warming subpolar North Atlantic Ocean and the increasing contribution to sea level rise due to ice mass loss from the Greenland Ice Sheet multiple hydrographic and bathymetric surveys were conducted in the summer 2015 under the aegis of the NASA sub-orbital mission, Oceans Melting Greenland (OMG). Here, we report for the first time on the spatial variations of the hydrographic properties of the warm, subsurface subtropical-origin waters penetrating the numerous previously unmapped glacial fjords of Northwest Greenland spanning more than 1000 km of coast between Upernavik Fjord (73°N) and Inglefield Gulf (77.5°N). To interpret the distribution of hydrographic properties of these warm subsurface waters above the inner continental shelf and within glacial fjords, we analyze more than 5500 km of new high-resolution swath bathymetry and 1000 km of single-beam bathymetry data. These new bathymetry data reveal a network of deep troughs within which warm subsurface waters can penetrate from the continental shelf into glacial fjords and numerous shallow sills and ledges that inhibit the warm water contact with glacial termini. While these new hydrographic data are synoptic and therefore cannot reveal information about hydrographic temporal variability, the positive identification of warm waters in some glacial fjords in mid to late summer when subglacial discharge-fueled submarine melting is greatest provides useful information about the vulnerability of certain marine-terminating glaciers to future ocean-forced thinning, retreat, and acceleration.