nerc.ac.uk

Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements

Dunse, T.; Schuler, T.V.; Hagen, J.O.; Reijmer, C.H.. 2012 Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements. The Cryosphere, 6 (2). 453-466. https://doi.org/10.5194/tc-6-453-2012

Before downloading, please read NORA policies.
[img]
Preview
Text
tc-6-453-2012.pdf - Published Version

Download (2MB) | Preview

Abstract/Summary

A large part of the ice discharge from ice caps and ice sheets occurs through spatially limited flow units that may operate in a mode of steady flow or cyclic surge behaviour. Changes in the dynamics of distinct flow units play a key role in the mass balance of Austfonna, the largest ice cap on Svalbard. The recent net mass loss of Austfonna was dominated by calving from marine terminating outlet glaciers. Previous ice-surface velocity maps of the ice cap were derived by satellite radar interferometry (InSAR) and rely on data acquired in the mid-1990s with limited information concerning the temporal variability. Here, we present continuous Global Positioning System (GPS) observations along the central flowlines of two fast flowing outlet glaciers over 2008–2010. The data show prominent summer speed-ups with ice-surface velocities as high as 240% of the pre-summer mean. Acceleration follows the onset of the summer melt period, indicating enhanced basal motion due to input of surface meltwater into the subglacial drainage system. In 2008, multiple velocity peaks coincide with successive melt periods. In 2009, the major melt was of higher amplitude than in 2008. Flow velocities appear unaffected by subsequent melt periods, suggesting a transition towards a hydraulically more efficient drainage system. The observed annual mean velocities of Duvebreen and Basin-3 exceed those from the mid-1990s by factors two and four, respectively, implying increased ice discharge at the calving front. Measured summer velocities up to 2 m d−1 for Basin-3 are close to those of Kronebreen, often referred to as the fastest glacier on Svalbard.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.5194/tc-6-453-2012
Programmes: BAS Programmes > EU:Ice2Sea
ISSN: 1994-0424
Additional Information. Not used in RCUK Gateway to Research.: open access journal
Date made live: 13 Dec 2012 11:54 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/20801

Actions (login required)

View Item View Item

Document Downloads

Downloads for past 30 days

Downloads per month over past year

More statistics for this item...