Towards a mesoscale eddy closure

Eden, Carsten and Greatbatch, Richard (2008) Towards a mesoscale eddy closure Ocean Modelling, 20 (3). pp. 223-239. DOI 10.1016/j.ocemod.2007.09.002.

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Abstract

Zusammenfassung
A turbulence closure for the effect of mesoscale eddies in non-eddy-resolving ocean models is proposed. The closure consists of a prognostic equation for the eddy kinetic energy (EKE) that is integrated as an additional model equation, and a diagnostic relation for an eddy length scale (L), which is given by the minimum of Rhines scale and Rossby radius. Combining EKE and L using a standard mixing length assumption gives a diffusivity (K), corresponding to the thickness diffusivity in the [Gent, P.R., McWilliams, J.C. 1990. Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr. 20, 150-155] parameterisation. Assuming downgradient mixing of potential vorticity with identical diffusivity shows how K is related to horizontal and vertical mixing processes in the horizontal momentum equation, and also enables us to parameterise the source of EKE related to eddy momentum fluxes. The mesoscale eddy closure is evaluated using synthetic data from two different eddy-resolving models covering the North Atlantic Ocean and the Southern Ocean, respectively. The diagnosis shows that the mixing length assumption together with the definition of eddy length scales is valid within certain limitations. Furthermore, implementation of the closure in non-eddy-resolving models of the North Atlantic and the Southern Ocean shows consistently that the closure has skill at reproducing the results of the eddy-resolving model versions in terms of EKE and K.

Document Type: Article
Keywords: OCEAN CIRCULATION MODELS; DYNAMICAL MODEL; GENERAL-CIRCULATION; ENERGY CASCADE; PART II; EDDIES; TURBULENCE; EQUATION; TRACER; FLUXES
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
DOI etc.: 10.1016/j.ocemod.2007.09.002
ISSN: 1463-5003
Projects: Future Ocean
Date Deposited: 03 Dec 2008 16:52
Last Modified: 13 Feb 2017 10:20
URI: http://eprints.uni-kiel.de/id/eprint/2504

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