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| Titel |
Simulating the retreat of the freshwater calving Glacier O'Higgins using a flow line model |
| VerfasserIn |
Marius Schaefer, Gino Casassa, Thomas Loriaux |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250056642
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| Zusammenfassung |
| Glacier O’Higgins is an outlet glacier on the Eastern side of the Southern Patagonia Icefield
which calves into Lake O’Higgins. The glacier has shown a very rapid retreat of about 15
kilometres during the last century. The retreat is thought to be triggered by warming
climate. This caused the front, initially anchored on a small island, to retreat into
deeper water, which strongly accelerated the retreat. We simulate the dynamics of the
glacier with a vertically and laterally averaged flow-line model. The shallow ice
approximation is employed and a constant rheological factor is assumed in Nye’s
flow law justified by uniform temperature distribution in the temperate O’Higgins
Glacier. A Weertman-type sliding law is assumed. The maximum stand of the glacier
during the last 100 years can be modelled by imposing a cooler climate forcing
with a lower equilibrium line altitude (ELA) in comparison to the present. Model
parameters are optimized by matching the modelled ice depth with the trim lines of the
maximum stand. Subsequently a warmer climate with a lower ELA is imposed and the
retreat of the front is modelled. Different calving models are tested to reproduce the
historic record of the frontal retreat. An outlook is undertaken in order to understand
how the glacier will evolve under different future climate forcings and assess its
contribution to sea-level rise. We conclude that the initial retreat was caused by a slightly
warmer climate but the rapid retreat during the last century is rather due to dynamical
mechanisms than due to climate forcing per se. The flow line model proves to be a simple
but appropriate tool to model these dynamical mechanisms of glacier behaviour. |
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