Towards a potential vorticity based mesoscale closure scheme
International audience With the advent of high-performance computing, we are now capable of simulating the ocean and climate system on decadal to centennial timescales. However, global and basin-scale simulations still lack the spatial resolution necessary to resolve the mesoscales (hereon referred...
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ftinsu:oai:HAL:hal-04549960v1 2024-10-06T13:51:16+00:00 Towards a potential vorticity based mesoscale closure scheme Uchida, Takaya Jamet, Quentin Dewar, William Balwada, Dhruv Le Sommer, Julien Penduff, Thierry Institut des Géosciences de l’Environnement (IGE) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP) Université Grenoble Alpes (UGA) Online/Vienna, Austria 2021-04 https://hal.science/hal-04549960 https://doi.org/10.5194/egusphere-egu21-70 en eng HAL CCSD info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu21-70 EGU General Assembly https://hal.science/hal-04549960 EGU General Assembly, Apr 2021, Online/Vienna, Austria. ⟨10.5194/egusphere-egu21-70⟩ [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography info:eu-repo/semantics/conferenceObject Conference papers 2021 ftinsu https://doi.org/10.5194/egusphere-egu21-70 2024-09-26T15:02:33Z International audience With the advent of high-performance computing, we are now capable of simulating the ocean and climate system on decadal to centennial timescales. However, global and basin-scale simulations still lack the spatial resolution necessary to resolve the mesoscales (hereon referred to as mesoscale-permitting simulations), a scale roughly on the order of O(100 km). Here, we provide a first step towards a potential vorticity (PV) based mesoscale closure scheme in order to improve the representation of mesoscale eddies in such simulations by taking advantage of the thickness-weighted averaged (TWA) framework. In the TWA framework the total eddy feedback can be encapsulated in the Eliassen-Palm (E-P) flux divergence. This implies that mesoscale closure schemes aimed at representing the total eddy feedback should therefore be representing the E-P flux divergence. The TWA framework further elucidates that its divergence is equivalent to the eddy Ertel PV flux. In other words, if one is to parametrize the eddy Ertel PV flux, one has parametrized the total eddy feedback onto the mean flow. Using a 1/12° North Atlantic ensemble simulation with 24 members, which allows us to decompose the mesoscale variability from the forced dynamics, we show that the eddy Ertel PV flux can be related to the local-gradient of mean Ertel PV as an active tracer via an anisotropic eddy diffusivity tensor. What follows is that not only does the tensor bring together the isopycnal thickness skew diffusivity and isopycnic tracer diffusivity, the former known as the Gent-McWilliams (GM) parametrization and latter the Redi parametrization, but also incorporates the eddy momentum fluxes. Although the Redi parametrization has existed longer than GM, there has been much more development in the latter, leaving the Redi diffusivity poorly constrained. Being able to treat GM and Redi simultaneously is another strength of our framework. Conference Object North Atlantic Institut national des sciences de l'Univers: HAL-INSU |
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Open Polar |
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Institut national des sciences de l'Univers: HAL-INSU |
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language |
English |
topic |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
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[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography Uchida, Takaya Jamet, Quentin Dewar, William Balwada, Dhruv Le Sommer, Julien Penduff, Thierry Towards a potential vorticity based mesoscale closure scheme |
topic_facet |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
description |
International audience With the advent of high-performance computing, we are now capable of simulating the ocean and climate system on decadal to centennial timescales. However, global and basin-scale simulations still lack the spatial resolution necessary to resolve the mesoscales (hereon referred to as mesoscale-permitting simulations), a scale roughly on the order of O(100 km). Here, we provide a first step towards a potential vorticity (PV) based mesoscale closure scheme in order to improve the representation of mesoscale eddies in such simulations by taking advantage of the thickness-weighted averaged (TWA) framework. In the TWA framework the total eddy feedback can be encapsulated in the Eliassen-Palm (E-P) flux divergence. This implies that mesoscale closure schemes aimed at representing the total eddy feedback should therefore be representing the E-P flux divergence. The TWA framework further elucidates that its divergence is equivalent to the eddy Ertel PV flux. In other words, if one is to parametrize the eddy Ertel PV flux, one has parametrized the total eddy feedback onto the mean flow. Using a 1/12° North Atlantic ensemble simulation with 24 members, which allows us to decompose the mesoscale variability from the forced dynamics, we show that the eddy Ertel PV flux can be related to the local-gradient of mean Ertel PV as an active tracer via an anisotropic eddy diffusivity tensor. What follows is that not only does the tensor bring together the isopycnal thickness skew diffusivity and isopycnic tracer diffusivity, the former known as the Gent-McWilliams (GM) parametrization and latter the Redi parametrization, but also incorporates the eddy momentum fluxes. Although the Redi parametrization has existed longer than GM, there has been much more development in the latter, leaving the Redi diffusivity poorly constrained. Being able to treat GM and Redi simultaneously is another strength of our framework. |
author2 |
Institut des Géosciences de l’Environnement (IGE) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP) Université Grenoble Alpes (UGA) |
format |
Conference Object |
author |
Uchida, Takaya Jamet, Quentin Dewar, William Balwada, Dhruv Le Sommer, Julien Penduff, Thierry |
author_facet |
Uchida, Takaya Jamet, Quentin Dewar, William Balwada, Dhruv Le Sommer, Julien Penduff, Thierry |
author_sort |
Uchida, Takaya |
title |
Towards a potential vorticity based mesoscale closure scheme |
title_short |
Towards a potential vorticity based mesoscale closure scheme |
title_full |
Towards a potential vorticity based mesoscale closure scheme |
title_fullStr |
Towards a potential vorticity based mesoscale closure scheme |
title_full_unstemmed |
Towards a potential vorticity based mesoscale closure scheme |
title_sort |
towards a potential vorticity based mesoscale closure scheme |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://hal.science/hal-04549960 https://doi.org/10.5194/egusphere-egu21-70 |
op_coverage |
Online/Vienna, Austria |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
EGU General Assembly https://hal.science/hal-04549960 EGU General Assembly, Apr 2021, Online/Vienna, Austria. ⟨10.5194/egusphere-egu21-70⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu21-70 |
op_doi |
https://doi.org/10.5194/egusphere-egu21-70 |
_version_ |
1812179477323579392 |