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| Titel |
Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements |
| VerfasserIn |
T. Dunse, T. V. Schuler, J. O. Hagen, C. H. Reijmer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 6, no. 2 ; Nr. 6, no. 2 (2012-04-10), S.453-466 |
| Datensatznummer |
250003491
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| Publikation (Nr.) |
 copernicus.org/tc-6-453-2012.pdf |
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| Zusammenfassung |
| 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. |
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