Simulating the roles of crevasse routing of surface water and basal friction on the surge evolution of Basin 3, Austfonna ice cap

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Gong , Y , Zwinger , T , Åström , J , Altena , B , Schellenberger , T , Gladstone , R & Moore , J 2018 , ' Simulating the roles of crevasse routing of surface water and basal friction on the surge evolution of Basin 3, Austfonna ice cap ' , Cryosphere , vol. 12 , no. 5 , pp. 1563-1577 . https://doi.org/10.5194/tc-12-1563-2018

Title: Simulating the roles of crevasse routing of surface water and basal friction on the surge evolution of Basin 3, Austfonna ice cap
Author: Gong, Yongmei; Zwinger, Thomas; Åström, Jan; Altena, Bas; Schellenberger, Thomas; Gladstone, Rupert; Moore, John
Contributor organization: INAR Physics
Institute for Atmospheric and Earth System Research (INAR)
Date: 2018-05-03
Language: eng
Number of pages: 15
Belongs to series: Cryosphere
ISSN: 1994-0416
DOI: https://doi.org/10.5194/tc-12-1563-2018
URI: http://hdl.handle.net/10138/278908
Abstract: The marine-terminating outlet in Basin 3, Austfonna ice cap, has been accelerating since the mid-1990s. Stepwise multi-annual acceleration associated with seasonal summer speed-up events was observed before the outlet entered the basin-wide surge in autumn 2012. We used multiple numerical models to explore hydrologic activation mechanisms for the surge behaviour. A continuum ice dynamic model was used to invert basal friction coefficient distributions using the control method and observed surface velocity data between April 2012 and July 2014. This has provided input to a discrete element model capable of simulating individual crevasses, with the aim of finding locations where meltwater entered the glacier during the summer and reached the bed. The possible flow paths of surface meltwater reaching the glacier bed as well as those of meltwater produced at the bed were calculated according to the gradient of the hydraulic potential. The inverted friction coefficients show the "unplugging" of the stagnant ice front and expansion of low-friction regions before the surge reached its peak velocity in January 2013. Crevasse distribution reflects the basal friction pattern to a high degree. The meltwater reaches the bed through the crevasses located above the margins of the subglacial valley and the basal melt that is generated mainly by frictional heating flows either to the fast-flowing units or potentially accumulates in an overdeepened region. Based on these results, the mechanisms facilitated by basal meltwater production, crevasse opening and the routing of meltwater to the bed are discussed for the surge in Basin 3.
Subject: 1171 Geosciences
SEA-LEVEL RISE
OUTLET GLACIERS
FRACTURE-MECHANICS
SHEET MODEL
FAST-FLOW
SVALBARD
GREENLAND
DYNAMICS
MELT
TRANSFORM
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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