文章基本信息

标题：On the numerical resolution of the bottom layer in simulations of oceanic gravity currents
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作者：Laanaia, N. ; Wirth, A. ; Molines, J. M. 等
期刊名称：Ocean Science
印刷版ISSN：1812-0784
电子版ISSN：1812-0792
出版年度：2010
卷号：6
期号：2
页码：563-572
DOI：10.5194/os-6-563-2010
出版社：Copernicus Publications
摘要：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.