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Annual down-glacier drainage of lakes and water-filled crevasses at Helheim Glacier, southeast Greenland

Alistair Everett, Tavi Murray Orcid Logo, Nick Selmes Orcid Logo, I. C. Rutt, Adrian Luckman Orcid Logo, Jonathan James, C. Clason, M. O'Leary, Harshinie Karunarathna Orcid Logo, V. Moloney, Dominic Reeve Orcid Logo

Journal of Geophysical Research: Earth Surface, Volume: 121, Issue: 10, Pages: 1819 - 1833

Swansea University Authors: Alistair Everett, Tavi Murray Orcid Logo, Nick Selmes Orcid Logo, Adrian Luckman Orcid Logo, Jonathan James, Harshinie Karunarathna Orcid Logo, Dominic Reeve Orcid Logo

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DOI (Published version): 10.1002/2016jf003831

Abstract

Supraglacial lake drainage events are common on the Greenland ice sheet. Observations on the west coast typically show an up-glacier progression of drainage as the annual melt extent spreads inland. We use a suite of remote sensing and modeling techniques in order to study a series of lakes and wate...

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Published in: Journal of Geophysical Research: Earth Surface
ISSN: 2169-9003
Published: American Geophysical Union (AGU) 2016
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa30225
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Abstract: Supraglacial lake drainage events are common on the Greenland ice sheet. Observations on the west coast typically show an up-glacier progression of drainage as the annual melt extent spreads inland. We use a suite of remote sensing and modeling techniques in order to study a series of lakes and water-filled crevasses within 20 km of the terminus of Helheim Glacier, southeast Greenland. Automatic classification of surface water areas shows a down-glacier progression of drainage, which occurs in the majority of years between 2007 and 2014. We demonstrate that a linear elastic fracture mechanics model can reliably predict the drainage of the uppermost supraglacial lake in the system but cannot explain the pattern of filling and draining observed in areas of surface water downstream. We propose that the water levels in crevasses downstream of the supraglacial lake can be explained by a transient high-pressure wave passing through the subglacial system following the lake drainage. We support this hypothesis with analysis of the subglacial hydrological conditions, which can explain both the position and interannual variation in filling order of these crevasses. Similar behavior has been observed in association with jökulhaups, surging glaciers, and Antarctic subglacial lakes but has not previously been observed on major outlets of the Greenland ice sheet. Our results suggest that the behavior of near-terminus surface water may differ considerably from that of inland supraglacial lakes, with the potential for basal water pressures to influence the presence of surface water in crevasses close to the terminus of tidewater glaciers.
Keywords: Greenland ice sheet; subglacial hydrology; water-filled crevasses
College: College of Science
Issue: 10
Start Page: 1819
End Page: 1833