Towards a mesoscale eddy closure
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...
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Online Access: | http://hdl.handle.net/11858/00-001M-0000-0017-C9E2-6 |
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ftpubman:oai:pure.mpg.de:item_1920655 2024-09-09T19:56:22+00:00 Towards a mesoscale eddy closure Eden, C. Greatbatch, R. 2008 http://hdl.handle.net/11858/00-001M-0000-0017-C9E2-6 eng eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.ocemod.2007.09.002 http://hdl.handle.net/11858/00-001M-0000-0017-C9E2-6 OCEAN MODELLING info:eu-repo/semantics/article 2008 ftpubman https://doi.org/10.1016/j.ocemod.2007.09.002 2024-07-31T09:31:27Z 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. (c) 2007 Elsevier Ltd. All rights reserved. Article in Journal/Newspaper North Atlantic Southern Ocean Max Planck Society: MPG.PuRe Southern Ocean Ocean Modelling 20 3 223 239 |
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Max Planck Society: MPG.PuRe |
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ftpubman |
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English |
description |
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. (c) 2007 Elsevier Ltd. All rights reserved. |
format |
Article in Journal/Newspaper |
author |
Eden, C. Greatbatch, R. |
spellingShingle |
Eden, C. Greatbatch, R. Towards a mesoscale eddy closure |
author_facet |
Eden, C. Greatbatch, R. |
author_sort |
Eden, C. |
title |
Towards a mesoscale eddy closure |
title_short |
Towards a mesoscale eddy closure |
title_full |
Towards a mesoscale eddy closure |
title_fullStr |
Towards a mesoscale eddy closure |
title_full_unstemmed |
Towards a mesoscale eddy closure |
title_sort |
towards a mesoscale eddy closure |
publishDate |
2008 |
url |
http://hdl.handle.net/11858/00-001M-0000-0017-C9E2-6 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_source |
OCEAN MODELLING |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.ocemod.2007.09.002 http://hdl.handle.net/11858/00-001M-0000-0017-C9E2-6 |
op_doi |
https://doi.org/10.1016/j.ocemod.2007.09.002 |
container_title |
Ocean Modelling |
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20 |
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3 |
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223 |
op_container_end_page |
239 |
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1809927043262971904 |