Dynamics of turbulent western-boundary currents at low latitude in a shallow-water model - Archive ouverte HAL Access content directly
Journal Articles Ocean Science Year : 2015

Dynamics of turbulent western-boundary currents at low latitude in a shallow-water model

(1, 2, 3) , (3)
1
2
3

Abstract

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 m 2 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 vor-ticity balance between the viscous transport and the advec-tive 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 .
Fichier principal
Vignette du fichier
OCEAN SCIENCE - Dynamics of turbulent western-boundary currents at low latitude in a shallow-water model.pdf (2.36 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive
Loading...

Dates and versions

insu-01275263 , version 1 (17-02-2016)

Identifiers

Cite

Cataria Quam Cyrille Akuetevi, Achim Wirth. Dynamics of turbulent western-boundary currents at low latitude in a shallow-water model. Ocean Science, 2015, 11, pp.471-481. ⟨10.5194/os-11-471-2015⟩. ⟨insu-01275263⟩
304 View
241 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More