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| Titel |
Interaction of marine ice-sheet instabilities in two drainage basins: simple scaling of geometry and transition time |
| VerfasserIn |
J. Feldmann, 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 ; 9, no. 2 ; Nr. 9, no. 2 (2015-04-02), S.631-645 |
| Datensatznummer |
250116774
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| Publikation (Nr.) |
 copernicus.org/tc-9-631-2015.pdf |
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| Zusammenfassung |
| The initiation of a marine ice-sheet instability (MISI) is generally
discussed from the ocean side of the ice sheet. It has been shown that the
reduction in ice-shelf buttressing and softening of the coastal ice can
destabilize a marine ice sheet if the bedrock is sloping upward towards the
ocean. Using a conceptional flow-line geometry, we investigate the
possibility of whether a MISI can be triggered from the direction of the ice
divide as opposed to coastal forcing and explore the interaction between
connected basins. We find that the initiation of a MISI in one basin can
induce a destabilization in the other. The underlying mechanism of basin
interaction is based on dynamic thinning and a consecutive motion of the ice
divide which induces a thinning in the adjacent basin and a successive
initiation of the instability. Our simplified and symmetric topographic setup
allows scaling both the geometry and the transition time between both
instabilities. We find that the ice profile follows a universal shape that is
scaled with the horizontal extent of the ice sheet and that the same exponent
of 1/2 applies for the scaling relation between central surface elevation
and horizontal extent as in the pure shallow ice approximation (Vialov
profile). Altering the central bed elevation, we find that the extent of
grounding-line retreat in one basin determines the degree of interaction with
the other. Different scenarios of basin interaction are discussed based on
our modeling results as well as on a conceptual flux-balance analysis. We
conclude that for the three-dimensional case, the possibility of drainage
basin interaction on timescales on the order of 1 kyr or larger cannot be
excluded and hence needs further investigation. |
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