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| Titel |
On the computation of the barotropic mode of a free-surface world ocean model |
| VerfasserIn |
E. Deleersnijder, J.-M. Campin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 13, no. 6 ; Nr. 13, no. 6, S.675-688 |
| Datensatznummer |
250011890
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| Publikation (Nr.) |
 copernicus.org/angeo-13-675-1995.pdf |
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| Zusammenfassung |
| The free-surface formulation of the equations
of our world ocean model is briefly described. The barotropic mode equations are
solved according to the split-explicit method, using different time steps for
the external and internal modes. Because the numerical algorithm is implemented
on the B-grid, a spurious, free-surface, two-grid interval mode may develop.
This mode must be filtered out. The properties of two filters are theoretically
investigated and their actual performance is tested in a series of numerical
experiments. It is seen that one of these filters may severely perturb the local
mass conservation, rendering it impossible to enforce the impermeability of the
surface or the bottom of the ocean. The dynamics of the external mode is also
examined, by studying the depth-integrated momentum equations. The
depth-integral of the pressure force due to the slope of the ocean surface is
approximately balanced by the depth-integral of the force ensuing from the
horizontal variations of the density. The depth-integral of the Coriolis force
is an order of magnitude smaller, except in the Southern Ocean. Two variational
principles are resorted to for computing the fictitious ocean surface elevation
corresponding to the approximate equilibrium between the dominant forces of the
barotropic momentum equations. |
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