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| Titel |
Kinematic first-order calving law implies potential for abrupt ice-shelf retreat |
| VerfasserIn |
A. Levermann, T. Albrecht, R. Winkelmann, M. A. Martin, M. Haseloff, I. Joughin |
| 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 (2012-03-13), S.273-286 |
| Datensatznummer |
250003477
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| Publikation (Nr.) |
 copernicus.org/tc-6-273-2012.pdf |
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| Zusammenfassung |
| Recently observed large-scale disintegration of Antarctic ice shelves has
moved their fronts closer towards grounded ice. In response, ice-sheet
discharge into the ocean has accelerated, contributing to global sea-level
rise and emphasizing the importance of calving-front dynamics. The position
of the ice front strongly influences the stress field within the entire
sheet-shelf-system and thereby the mass flow across the grounding line. While
theories for an advance of the ice-front are readily available, no general
rule exists for its retreat, making it difficult to incorporate the retreat
in predictive models. Here we extract the first-order large-scale kinematic
contribution to calving which is consistent with large-scale observation. We
emphasize that the proposed equation does not constitute a comprehensive
calving law but represents the first-order kinematic contribution which can
and should be complemented by higher order contributions as well as the
influence of potentially heterogeneous material properties of the ice. When
applied as a calving law, the equation naturally incorporates the stabilizing
effect of pinning points and inhibits ice shelf growth outside of embayments.
It depends only on local ice properties which are, however, determined by the
full topography of the ice shelf. In numerical simulations the
parameterization reproduces multiple stable fronts as observed for the Larsen
A and B Ice Shelves including abrupt transitions between them which may be
caused by localized ice weaknesses. We also find multiple stable states of
the Ross Ice Shelf at the gateway of the West Antarctic Ice Sheet with back
stresses onto the sheet reduced by up to 90 % compared to the present state. |
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