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| Titel |
Dynamics of turbulent western-boundary currents at low latitude in a shallow-water model |
| VerfasserIn |
C. Q. C. Akuetevi, A. Wirth |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 11, no. 3 ; Nr. 11, no. 3 (2015-06-26), S.471-481 |
| Datensatznummer |
250117229
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| Publikation (Nr.) |
 copernicus.org/os-11-471-2015.pdf |
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| Zusammenfassung |
| The dynamics of low latitude turbulent western-boundary currents (WBCs) crossing the
Equator are considered using numerical results from integrations of a reduced-gravity shallow-water model. For viscosity values of 1000 m2 s−1 and
greater, the boundary layer dynamics compares well to the analytical Munk-layer
solution. When the viscosity is reduced, the boundary layer becomes turbulent
and coherent structures in the form of anticyclonic eddies, bursts (violent
detachments of the viscous sub-layer, VSL) and dipoles appear. Three distinct
boundary layers emerge, the VSL, the advective boundary layer
and the extended boundary layer. The first is characterized by a dominant
vorticity balance between the viscous transport and the advective transport
of vorticity; the second by a balance between the advection of planetary
vorticity and the advective transport of relative vorticity. The extended
boundary layer is the area to which turbulent motion from the boundary
extends. The scaling of the three boundary layer thicknesses with viscosity
is evaluated. Characteristic scales of the dynamics and dissipation are
determined.
A pragmatic approach to determine the eddy viscosity diagnostically for
coarse-resolution numerical models is proposed. |
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