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On the Numerical Resolution of the Bottom Layer in Simulations of Oceanic Gravity Currents : Volume 7, Issue 2 (04/03/2010)

By Laanaia, N.

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Book Id: WPLBN0003981033
Format Type: PDF Article :
File Size: Pages 28
Reproduction Date: 2015

Title: On the Numerical Resolution of the Bottom Layer in Simulations of Oceanic Gravity Currents : Volume 7, Issue 2 (04/03/2010)  
Author: Laanaia, N.
Volume: Vol. 7, Issue 2
Language: English
Subject: Science, Ocean, Science
Collections: Periodicals: Journal and Magazine Collection (Contemporary), Copernicus GmbH
Publication Date:
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications


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Verron, J., Barnier, B., Laanaia, N., Wirth, A., & Molines, J. M. (2010). On the Numerical Resolution of the Bottom Layer in Simulations of Oceanic Gravity Currents : Volume 7, Issue 2 (04/03/2010). Retrieved from

Description: LEGI/MEOM/CNRS-INSU, UMR 5519, Grenoble, France. The role of an increased numerical vertical resolution, leading to an explicit resolution of the bottom Ekman layer dynamics, is investigated. Using the hydrostatic ocean model NEMO-OPA9, we demonstrate that the dynamics of an idealised gravity current (on an inclined plane), is well captured when a few (around five) sigma-coordinate levels are added near the ocean floor. Such resolution allows to considerably improve the representation of the descent and transport of the gravity current and the Ekman dynamics near the ocean floor, including the important effect of Ekman veering, which is usually neglected in today's simulations of the ocean dynamics.

Results from high resolution simulations (with σ and z-coordinates) are compared to simulations with a vertical resolution commonly employed in today's ocean models. The latter show a downslope transport that is reduced by almost an order of magnitude and the decrease in the along slope transport is reduced six-fold. We strongly advocate for an increase of the numerical resolution at the ocean floor, similar to the way it is done at the ocean surface and at the lower boundary in atmospheric models.

On the numerical resolution of the bottom layer in simulations of oceanic gravity currents

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