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Importance of basal processes in simulations of a surging Svalbard outlet glacier

Citation

Gladstone, R and Schafer, M and Zwinger, T and Gong, Y and Strozzi, T and Mottram, RH and Boberg, F and Moore, JC, Importance of basal processes in simulations of a surging Svalbard outlet glacier, Cryosphere, 8, (4) pp. 1393-1405. ISSN 1994-0416 (2014) [Refereed Article]


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Licensed under Creative Commons Attribution 3.0 Unported http://creativecommons.org/licenses/by/3.0/legalcode

DOI: doi:10.5194/tc-8-1393-2014

Abstract

The outlet glacier of Basin 3 (B3) of Austfonna ice cap, Svalbard, is one of the fastest outlet glaciers in Svalbard, and shows dramatic changes since 1995. In addition to previously observed seasonal summer speed-up associated with the melt season, the winter speed of B3 has accelerated approximately fivefold since 1995. We use the Elmer/Ice full-Stokes model for ice dynamics to infer spatial distributions of basal drag for the winter seasons of 1995, 2008 and 2011. This "inverse" method is based on minimising discrepancy between modelled and observed surface velocities, using satellite remotely sensed velocity fields. We generate steady-state temperature distributions for 1995 and 2011. Frictional heating caused by basal sliding contributes significantly to basal temperatures of the B3 outlet glacier, with heat advection (a longer-timescale process than frictional heating) also being important in the steady state.

We present a sensitivity experiment consisting of transient simulations under present-day forcing to demonstrate that using a temporally fixed basal drag field obtained through inversion can lead to thickness change errors of the order of 2 m yearg -1. Hence it is essential to incorporate the evolution of basal processes in future projections of the evolution of B3. Informed by a combination of our inverse method results and previous studies, we hypothesise a system of processes and feedbacks involving till deformation and basal hydrology to explain both the seasonal accelerations (short residence time pooling of meltwater at the ice-till interface) and the ongoing interannual speed-up (gradual penetration of water into the till, reducing till strength). © Author(s) 2014. CC Attribution 3.0 License.

Item Details

Item Type:Refereed Article
Keywords:Svalbard outlet glacier, Austfonna ice cap, Svalbard, ice dynamics, basal drag
Research Division:Earth Sciences
Research Group:Physical Geography and Environmental Geoscience
Research Field:Glaciology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Gladstone, R (Mr Rupert Gladstone)
ID Code:94519
Year Published:2014
Web of Science® Times Cited:3
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2014-09-10
Last Modified:2017-10-30
Downloads:228 View Download Statistics

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