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| Titel |
Fracture-induced softening for large-scale ice dynamics |
| VerfasserIn |
T. Albrecht, A. Levermann |
| 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. 2 ; Nr. 8, no. 2 (2014-04-08), S.587-605 |
| Datensatznummer |
250116088
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| Publikation (Nr.) |
 copernicus.org/tc-8-587-2014.pdf |
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| Zusammenfassung |
| Floating ice shelves can exert a retentive and hence stabilizing force onto
the inland ice sheet of Antarctica. However, this effect has been observed to
diminish by the dynamic effects of fracture processes within the protective
ice shelves, leading to accelerated ice flow and hence to a sea-level
contribution. In order to account for the macroscopic effect of fracture
processes on large-scale viscous ice dynamics (i.e., ice-shelf scale) we apply
a continuum representation of fractures and related fracture growth into the
prognostic Parallel Ice Sheet Model (PISM) and compare the results to
observations. To this end we introduce a higher order accuracy advection
scheme for the transport of the two-dimensional fracture density across the
regular computational grid. Dynamic coupling of fractures and ice flow is
attained by a reduction of effective ice viscosity proportional to the
inferred fracture density. This formulation implies the possibility of
non-linear threshold behavior due to self-amplified fracturing in shear
regions triggered by small variations in the fracture-initiation threshold. As
a result of prognostic flow simulations, sharp across-flow velocity gradients
appear in fracture-weakened regions. These modeled gradients compare well in
magnitude and location with those in observed flow patterns. This model
framework is in principle expandable to grounded ice streams and provides
simple means of investigating climate-induced effects on fracturing (e.g.,
hydro fracturing) and hence on the ice flow. It further constitutes a
physically sound basis for an enhanced fracture-based calving
parameterization. |
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