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| Titel |
Changing basal conditions during the rapid speed-up of Jakobshavn Isbræ, Greenland |
| VerfasserIn |
Marijke Habermann, Martin Truffer, David Maxwell |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072103
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| Zusammenfassung |
| Jakobshavn Isbræ has a century-long record of observations, and together with the recent
rapid retreat of the ice front and the complete disintegration of its floating ice tongue, it is the
perfect natural experiment to learn more about the processes driving its dynamic
evolution. Here we use existing surface velocity and ice geometry data from the years
1994, 2000, 2005 and 2008 to infer basal yield stress distributions of Jakobshavn
Isbræ.
The Parallel Ice Sheet Model (PISM) is used as a forward model in a Tikhonov inversion.
The minimized cost function consists of a data-model misfit term and a model-norm term
which is weighted with a regularization parameter. The inverse problem is ill-posed and many
solutions for the basal yield stress exist. Parameter choices such as the regularization
parameter, the model norm, the ice softness and the initial estimate of basal yield stress
influence the solution. We discuss the impact of these choices on the resulting basal yield
stress field of Jakobshavn Isbræ to determine appropriate values for the inversions of the
different years.
The resulting basal yield stress distributions for each year are then analyzed with
particular focus on spatial features in the basal yield stress and the achieved data-model
misfit, and on changes along the center line. |
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