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Titel |
On the representation of gravity current dynamics in numerical ocean circulation models |
VerfasserIn |
N. Laanaia, A. Wirth, J. Verron, B. Barnier |
Konferenz |
EGU General Assembly 2009
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 11 (2009) |
Datensatznummer |
250023792
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Zusammenfassung |
The realism of the numerical modelling of the ocean dynamics depends on the capability of
the numerical models to correctly represent the important processes, at large and also at small
scales. The dynamics of gravity currents was identified as a key process governing the
strength of the thermohaline circulation and its heat transport from low to high latitudes.
Oceanic gravity currents are small scale processes, only about 100km wide and
a few hundred meters thick, that have a substantial impact on the global climate
dynamics.
Using the hydrostatic ocean model NEMO-OPA9, we demonstrate for the case of an
idealised gravity current (on an inclined plane), that its dynamics is well captured when a few
(less than ten) sigma-coordinate levels are added near the ocean floor. Results from
integrations with different grid types (z, sigma and z+sigma) are evaluated and
compared to non-hydrostatic calculations, laboratory experiments and observations. The
results correctly represent the descent of the vein and the Ekman dynamics near the
ocean floor, including the important effect of Ekman veering and arrested Ekman
layers which are usually neglected in today’s simulations of the ocean dynamics. |
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