Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations
Abstract In this study we demonstrate the potential of a kinetic energy backscatter scheme for use in global ocean simulations. Ocean models commonly employ (bi)harmonic eddy viscosities causing excessive dissipation of kinetic energy in eddy‐permitting simulations. Overdissipation not only affects...
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ftdoajarticles:oai:doaj.org/article:3b05bcc09609423cbe1498e6b9fc5d55 2023-05-15T13:38:16+02:00 Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations Stephan Juricke Sergey Danilov Nikolay Koldunov Marcel Oliver Dmitry Sidorenko 2020-01-01T00:00:00Z https://doi.org/10.1029/2019MS001855 https://doaj.org/article/3b05bcc09609423cbe1498e6b9fc5d55 EN eng American Geophysical Union (AGU) https://doi.org/10.1029/2019MS001855 https://doaj.org/toc/1942-2466 1942-2466 doi:10.1029/2019MS001855 https://doaj.org/article/3b05bcc09609423cbe1498e6b9fc5d55 Journal of Advances in Modeling Earth Systems, Vol 12, Iss 1, Pp n/a-n/a (2020) ocean kinetic energy backscatter subgrid eddy parametrization inverse energy cascade viscosity closure eddy‐permitting resolution Physical geography GB3-5030 Oceanography GC1-1581 article 2020 ftdoajarticles https://doi.org/10.1029/2019MS001855 2022-12-31T05:32:27Z Abstract In this study we demonstrate the potential of a kinetic energy backscatter scheme for use in global ocean simulations. Ocean models commonly employ (bi)harmonic eddy viscosities causing excessive dissipation of kinetic energy in eddy‐permitting simulations. Overdissipation not only affects the smallest resolved scales but also the generation of eddies through baroclinic instabilities, impacting the entire wave number spectrum. The backscatter scheme returns part of this overdissipated energy back into the resolved flow. We employ backscatter in the FESOM2 multiresolution ocean model with a quasi‐uniform 1/4° mesh. In multidecadal ocean simulations, backscatter increases eddy activity by a factor 2 or more, moving the simulation closer to observational estimates of sea surface height variability. Moreover, mean sea surface height, temperature, and salinity biases are reduced. This amounts to a globally averaged bias reduction of around 10% for each field, which is even larger in the Antarctic Circumpolar Current. However, in some regions such as the coastal Kuroshio, backscatter leads to a slight overenergizing of the flow and, in the Antarctic, to an unrealistic reduction of sea ice. Some of the bias increases can be reduced by a retuning of the model, and we suggest related adjustments to the backscatter scheme. The backscatter simulation is about 2.5 times as expensive as a simulation without backscatter. Most of the increased cost is due to a halving of the time step to accommodate higher simulated velocities. Article in Journal/Newspaper Antarc* Antarctic Sea ice Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic Journal of Advances in Modeling Earth Systems 12 1 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
ocean kinetic energy backscatter subgrid eddy parametrization inverse energy cascade viscosity closure eddy‐permitting resolution Physical geography GB3-5030 Oceanography GC1-1581 |
spellingShingle |
ocean kinetic energy backscatter subgrid eddy parametrization inverse energy cascade viscosity closure eddy‐permitting resolution Physical geography GB3-5030 Oceanography GC1-1581 Stephan Juricke Sergey Danilov Nikolay Koldunov Marcel Oliver Dmitry Sidorenko Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations |
topic_facet |
ocean kinetic energy backscatter subgrid eddy parametrization inverse energy cascade viscosity closure eddy‐permitting resolution Physical geography GB3-5030 Oceanography GC1-1581 |
description |
Abstract In this study we demonstrate the potential of a kinetic energy backscatter scheme for use in global ocean simulations. Ocean models commonly employ (bi)harmonic eddy viscosities causing excessive dissipation of kinetic energy in eddy‐permitting simulations. Overdissipation not only affects the smallest resolved scales but also the generation of eddies through baroclinic instabilities, impacting the entire wave number spectrum. The backscatter scheme returns part of this overdissipated energy back into the resolved flow. We employ backscatter in the FESOM2 multiresolution ocean model with a quasi‐uniform 1/4° mesh. In multidecadal ocean simulations, backscatter increases eddy activity by a factor 2 or more, moving the simulation closer to observational estimates of sea surface height variability. Moreover, mean sea surface height, temperature, and salinity biases are reduced. This amounts to a globally averaged bias reduction of around 10% for each field, which is even larger in the Antarctic Circumpolar Current. However, in some regions such as the coastal Kuroshio, backscatter leads to a slight overenergizing of the flow and, in the Antarctic, to an unrealistic reduction of sea ice. Some of the bias increases can be reduced by a retuning of the model, and we suggest related adjustments to the backscatter scheme. The backscatter simulation is about 2.5 times as expensive as a simulation without backscatter. Most of the increased cost is due to a halving of the time step to accommodate higher simulated velocities. |
format |
Article in Journal/Newspaper |
author |
Stephan Juricke Sergey Danilov Nikolay Koldunov Marcel Oliver Dmitry Sidorenko |
author_facet |
Stephan Juricke Sergey Danilov Nikolay Koldunov Marcel Oliver Dmitry Sidorenko |
author_sort |
Stephan Juricke |
title |
Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations |
title_short |
Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations |
title_full |
Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations |
title_fullStr |
Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations |
title_full_unstemmed |
Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations |
title_sort |
ocean kinetic energy backscatter parametrization on unstructured grids: impact on global eddy‐permitting simulations |
publisher |
American Geophysical Union (AGU) |
publishDate |
2020 |
url |
https://doi.org/10.1029/2019MS001855 https://doaj.org/article/3b05bcc09609423cbe1498e6b9fc5d55 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic Sea ice |
genre_facet |
Antarc* Antarctic Sea ice |
op_source |
Journal of Advances in Modeling Earth Systems, Vol 12, Iss 1, Pp n/a-n/a (2020) |
op_relation |
https://doi.org/10.1029/2019MS001855 https://doaj.org/toc/1942-2466 1942-2466 doi:10.1029/2019MS001855 https://doaj.org/article/3b05bcc09609423cbe1498e6b9fc5d55 |
op_doi |
https://doi.org/10.1029/2019MS001855 |
container_title |
Journal of Advances in Modeling Earth Systems |
container_volume |
12 |
container_issue |
1 |
_version_ |
1766103304091205632 |