Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements
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 Sval...
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ftunivutrecht:oai:dspace.library.uu.nl:1874/272821 2023-07-23T04:18:26+02:00 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. Marine and Atmospheric Research Sub Dynamics Meteorology 2012 text/plain https://dspace.library.uu.nl/handle/1874/272821 en eng 1994-0416 https://dspace.library.uu.nl/handle/1874/272821 info:eu-repo/semantics/OpenAccess Article 2012 ftunivutrecht 2023-07-02T00:37:09Z 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. Article in Journal/Newspaper Austfonna glacier Ice cap Svalbard Utrecht University Repository Austfonna ENVELOPE(24.559,24.559,79.835,79.835) Duvebreen ENVELOPE(23.905,23.905,80.150,80.150) Kronebreen ENVELOPE(13.333,13.333,78.833,78.833) Svalbard |
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Open Polar |
collection |
Utrecht University Repository |
op_collection_id |
ftunivutrecht |
language |
English |
description |
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. |
author2 |
Marine and Atmospheric Research Sub Dynamics Meteorology |
format |
Article in Journal/Newspaper |
author |
Dunse, T. Schuler, T.V. Hagen, J.O. Reijmer, C.H. |
spellingShingle |
Dunse, T. Schuler, T.V. Hagen, J.O. Reijmer, C.H. Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements |
author_facet |
Dunse, T. Schuler, T.V. Hagen, J.O. Reijmer, C.H. |
author_sort |
Dunse, T. |
title |
Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements |
title_short |
Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements |
title_full |
Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements |
title_fullStr |
Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements |
title_full_unstemmed |
Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements |
title_sort |
seasonal speed-up of two outlet glaciers of austfonna, svalbard, inferred from continuous gps measurements |
publishDate |
2012 |
url |
https://dspace.library.uu.nl/handle/1874/272821 |
long_lat |
ENVELOPE(24.559,24.559,79.835,79.835) ENVELOPE(23.905,23.905,80.150,80.150) ENVELOPE(13.333,13.333,78.833,78.833) |
geographic |
Austfonna Duvebreen Kronebreen Svalbard |
geographic_facet |
Austfonna Duvebreen Kronebreen Svalbard |
genre |
Austfonna glacier Ice cap Svalbard |
genre_facet |
Austfonna glacier Ice cap Svalbard |
op_relation |
1994-0416 https://dspace.library.uu.nl/handle/1874/272821 |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1772180759528865792 |