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Roles of Shear and Convection in Driving Mixing in the Ocean

Ivey, GN and Bluteau, CE and Gayen, B and Jones, NL and Sohail, T (2021) Roles of Shear and Convection in Driving Mixing in the Ocean. In: Geophysical Research Letters, 48 (3).

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Official URL: https://doi.org/10.1029/2020GL089455


Using field, numerical, and laboratory studies, we consider the roles of both shear and convection in driving mixing in the interior of the density-stratified ocean. Shear mixing dominates when the Richardson number Ri < 0.25, convective mixing dominates when Ri > 1.0, and in the intermediate regime when 0.25 < Ri < 1.0 both shear and convection can contribute to mixing. For pure shear mixing the mixing efficiency Rif approaches 0.5, while for pure convective mixing the mixing efficiency Rif approaches 0.75. The diapycnal diffusivities for the two mechanisms are given by very different expressions. Despite these complexities, a simple mixing length model using the mean flow shear S provides robust estimates of diffusivity across the range 0 < Ri < 2. To account for the roles of both shear and convection over this range of Ri, we also formulate a modified version of the empirical KPP model for parameterizing ocean mixing in numerical models. © 2020. The Authors.

Item Type: Journal Article
Publication: Geophysical Research Letters
Additional Information: The copyright for this article belongs to Authors
Keywords: Efficiency; Shear flow, Convective mixing; Density stratified; Diapycnal diffusivity; Intermediate regimes; Laboratory studies; Mean flow shear; Mixing efficiency; Richardson number, Mixing
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 31 Dec 2021 06:31
Last Modified: 31 Dec 2021 06:31
URI: http://eprints.iisc.ac.in/id/eprint/68188

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