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| Titel |
Importance of basal processes in simulations of a surging Svalbard outlet glacier |
| VerfasserIn |
R. Gladstone, M. Schäfer, T. Zwinger, Y. Gong, T. Strozzi, R. Mottram, F. Boberg, J. C. Moore |
| 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 ; 8, no. 4 ; Nr. 8, no. 4 (2014-08-04), S.1393-1405 |
| Datensatznummer |
250116255
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| Publikation (Nr.) |
 copernicus.org/tc-8-1393-2014.pdf |
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| Zusammenfassung |
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 year−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). |
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