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| Titel |
A comparison of the performance of 4D-Var in an explicit and implicit version of a nonlinear barotropic ocean model |
| VerfasserIn |
A. D. Terwisscha van Scheltinga, H. A. Dijkstra |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 14, no. 6 ; Nr. 14, no. 6 (2007-11-30), S.763-776 |
| Datensatznummer |
250012312
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| Publikation (Nr.) |
 copernicus.org/npg-14-763-2007.pdf |
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| Zusammenfassung |
| A comparison is made of the performance of the four-dimensional variational
data assimilation (4D-Var) method in an explicit and implicit version of a
barotropic quasi-geostrophic model of the wind-driven double-gyre ocean
circulation. As is well known, implicit methods have the advantage that
relatively large time steps can be taken with respect to explicit methods,
but the computational costs of each time step is larger. We focus here on two
issues: (i) the computational efficiency in the range of time steps where the
chosen explicit method is still numerically stable and (ii) the performance
of 4D-Var in the implicit model for time steps out of reach for the explicit
model. For the same time step Δt and the same number of points n
per assimilation interval, the analyses in the implicit model is always more
accurate than that in the explicit model. Due to this property the use of
4D-Var combined with the implicit model can be computationally more efficient
than its use in the explicit model. |
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