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doi:10.5194/osd-11-753-2014
© Author(s) 2014. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
05 Mar 2014
Review status
This discussion paper has been under review for the journal Ocean Science (OS). The revised manuscript was not accepted.
Dynamics of turbulent western boundary currents at low latitude in a shallow water model
C. Q. C. Akuetevi1,2 and A. Wirth1 1Univ. Grenoble Alpes, CNRS, LEGI UMR5519, Grenoble, France
2Univ. Grenoble Alpes, CNRS, LGGE UMR5183, Grenoble, France
Abstract. The dynamics of low latitude turbulent western boundary currents, subject to two different types of idealized wind forcing, Monsoon Wind and Trade Wind, is considered using numerical results from integrations of a reduced gravity shallow-water model. For viscosity values of 1000 m2 s−1 and above, the boundary layer dynamics compares well to the analytical solutions of the Munk-layer and the inertial-layer, derived from quasigeostrophic theory. Modifications due to variations in the layer thickness (vortex stretching) are only important close to the boundary. When the viscosity is reduced the boundary layer becomes turbulent and coherent structures in form of anticyclonic eddies, bursts (violent detachments of the viscous sub-layer) and dipoles appear. Three distinct boundary layers emerge, the viscous sub-layer, 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.

A pragmatic approach to determine the eddy viscosity diagnostically for coarse resolution numerical models is proposed.


Citation: Akuetevi, C. Q. C. and Wirth, A.: Dynamics of turbulent western boundary currents at low latitude in a shallow water model, Ocean Sci. Discuss., 11, 753-788, doi:10.5194/osd-11-753-2014, 2014.
C. Q. C. Akuetevi and A. Wirth
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
 
RC C109: 'Review', David Webb, 22 Mar 2014 Printer-friendly Version 
 
RC C288: 'Review', Anonymous Referee #2, 28 Apr 2014 Printer-friendly Version 
 
AC C402: 'Answer to reviewers', Cataria Quam Cyrille AKUETEVI, 26 May 2014 Printer-friendly Version Supplement 
C. Q. C. Akuetevi and A. Wirth
C. Q. C. Akuetevi and A. Wirth

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