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Titel |
Improved convergence and stability properties in a three-dimensional higher-order ice sheet model |
VerfasserIn |
J. J. Fürst, O. Rybak, H. Goelzer, B. Smedt, P. Groen, P. Huybrechts |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1991-959X
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Digitales Dokument |
URL |
Erschienen |
In: Geoscientific Model Development ; 4, no. 4 ; Nr. 4, no. 4 (2011-12-19), S.1133-1149 |
Datensatznummer |
250001924
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Publikation (Nr.) |
copernicus.org/gmd-4-1133-2011.pdf |
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Zusammenfassung |
We present a finite difference implementation of a three-dimensional
higher-order ice sheet model. In comparison to a conventional centred
difference discretisation it enhances both numerical stability and
convergence. In order to achieve these benefits the discretisation of the
governing force balance equation makes extensive use of information on
staggered grid points. Using the same iterative solver, a centred difference
discretisation that operates exclusively on the regular grid serves as a
reference. The reprise of the ISMIP-HOM experiments indicates that both
discretisations are capable of reproducing the higher-order model
inter-comparison results. This setup allows a direct comparison of the two
numerical implementations also with respect to their convergence behaviour.
First and foremost, the new finite difference scheme facilitates convergence
by a factor of up to 7 and 2.6 in average. In addition to this decrease in
computational costs, the accuracy for the resultant velocity field can be
chosen higher in the novel finite difference implementation. Changing the
discretisation also prevents build-up of local field irregularites that
occasionally cause divergence of the solution for the reference
discretisation.
The improved behaviour makes the new discretisation more reliable for
extensive application to real ice geometries. Higher accuracy and robust
numerics are crucial in time dependent applications since numerical
oscillations in the velocity field of subsequent time steps are attenuated
and divergence of the solution is prevented. |
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