Geostrophy Assessment and Momentum Balance of the Global Oceans in a Tide‐ and Eddy‐Resolving Model
International audience The future wide-swath satellite altimeters, such as the upcoming Surface Water Ocean Topography (SWOT) mission, will provide instantaneous 2D measurements of sea level down to the spatial scale of O(10 km) for the first time. However, the validity of the geostrophic assumption...
Published in: | Journal of Geophysical Research: Oceans |
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Main Authors: | , , , , |
Other Authors: | , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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HAL CCSD
2021
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Online Access: | https://hal.archives-ouvertes.fr/hal-03432358 https://doi.org/10.1029/2021JC017422 |
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Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
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ftccsdartic |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] Yu, Xiaolong Ponte, Aurélien Lahaye, Noé Caspar‐Cohen, Zoé Menemenlis, Dimitris Geostrophy Assessment and Momentum Balance of the Global Oceans in a Tide‐ and Eddy‐Resolving Model |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] |
description |
International audience The future wide-swath satellite altimeters, such as the upcoming Surface Water Ocean Topography (SWOT) mission, will provide instantaneous 2D measurements of sea level down to the spatial scale of O(10 km) for the first time. However, the validity of the geostrophic assumption for estimating surface currents from these instantaneous maps is not known a priori. In this study, we quantify the accuracy of geostrophy for the estimation of surface currents from a knowledge of instantaneous sea level using the hourly snapshots from a tide- and eddy-resolving global numerical simulation. Geostrophic balance is found to be the leading-order balance in frontal regions characterized by large kinetic energy, such as the western boundary currents and the Antarctic Circumpolar Current. Everywhere else, geostrophic approximation ceases to be a useful predictor of ocean velocity, which may result in significant high-frequency contamination of geostrophically computed velocities by fast variability (e.g., inertial and higher). As expected, the validity of geostrophy is shown to improve at low frequencies (typically urn:x-wiley:21699275:media:jgrc24720:jgrc24720-math-0001 0.5 cpd). Global estimates of the horizontal momentum budget reveal that the tropical and mid-latitude regions where geostrophic balance fails are dominated by fast variability and turbulent stress divergence terms rather than higher-order geostrophic terms. These findings indicate that the estimation of velocity from geostrophy applied on SWOT instantaneous sea level maps may be challenging away from energetic areas. |
author2 |
Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) Institut de Recherche Mathématique de Rennes (IRMAR) AGROCAMPUS OUEST Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université de Rennes 1 (UR1) Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Rennes 2 (UR2) Université de Rennes (UNIV-RENNES)-École normale supérieure - Rennes (ENS Rennes)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes) Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA) Fluid Flow Analysis, Description and Control from Image Sequences (FLUMINANCE) Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-AGROCAMPUS OUEST Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Inria Rennes – Bretagne Atlantique Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) Jet Propulsion Laboratory (JPL) NASA-California Institute of Technology (CALTECH) |
format |
Article in Journal/Newspaper |
author |
Yu, Xiaolong Ponte, Aurélien Lahaye, Noé Caspar‐Cohen, Zoé Menemenlis, Dimitris |
author_facet |
Yu, Xiaolong Ponte, Aurélien Lahaye, Noé Caspar‐Cohen, Zoé Menemenlis, Dimitris |
author_sort |
Yu, Xiaolong |
title |
Geostrophy Assessment and Momentum Balance of the Global Oceans in a Tide‐ and Eddy‐Resolving Model |
title_short |
Geostrophy Assessment and Momentum Balance of the Global Oceans in a Tide‐ and Eddy‐Resolving Model |
title_full |
Geostrophy Assessment and Momentum Balance of the Global Oceans in a Tide‐ and Eddy‐Resolving Model |
title_fullStr |
Geostrophy Assessment and Momentum Balance of the Global Oceans in a Tide‐ and Eddy‐Resolving Model |
title_full_unstemmed |
Geostrophy Assessment and Momentum Balance of the Global Oceans in a Tide‐ and Eddy‐Resolving Model |
title_sort |
geostrophy assessment and momentum balance of the global oceans in a tide‐ and eddy‐resolving model |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://hal.archives-ouvertes.fr/hal-03432358 https://doi.org/10.1029/2021JC017422 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
ISSN: 2169-9275 EISSN: 2169-9291 Journal of Geophysical Research. Oceans https://hal.archives-ouvertes.fr/hal-03432358 Journal of Geophysical Research. Oceans, Wiley-Blackwell, 2021, 126 (10), pp.1-19. ⟨10.1029/2021JC017422⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2021JC017422 hal-03432358 https://hal.archives-ouvertes.fr/hal-03432358 doi:10.1029/2021JC017422 |
op_doi |
https://doi.org/10.1029/2021JC017422 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
126 |
container_issue |
10 |
_version_ |
1766261001995419648 |
spelling |
ftccsdartic:oai:HAL:hal-03432358v1 2023-05-15T13:54:52+02:00 Geostrophy Assessment and Momentum Balance of the Global Oceans in a Tide‐ and Eddy‐Resolving Model Yu, Xiaolong Ponte, Aurélien Lahaye, Noé Caspar‐Cohen, Zoé Menemenlis, Dimitris Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) Institut de Recherche Mathématique de Rennes (IRMAR) AGROCAMPUS OUEST Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université de Rennes 1 (UR1) Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Rennes 2 (UR2) Université de Rennes (UNIV-RENNES)-École normale supérieure - Rennes (ENS Rennes)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes) Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA) Fluid Flow Analysis, Description and Control from Image Sequences (FLUMINANCE) Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-AGROCAMPUS OUEST Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Inria Rennes – Bretagne Atlantique Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) Jet Propulsion Laboratory (JPL) NASA-California Institute of Technology (CALTECH) 2021-10 https://hal.archives-ouvertes.fr/hal-03432358 https://doi.org/10.1029/2021JC017422 en eng HAL CCSD Wiley-Blackwell info:eu-repo/semantics/altIdentifier/doi/10.1029/2021JC017422 hal-03432358 https://hal.archives-ouvertes.fr/hal-03432358 doi:10.1029/2021JC017422 ISSN: 2169-9275 EISSN: 2169-9291 Journal of Geophysical Research. Oceans https://hal.archives-ouvertes.fr/hal-03432358 Journal of Geophysical Research. Oceans, Wiley-Blackwell, 2021, 126 (10), pp.1-19. ⟨10.1029/2021JC017422⟩ [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] info:eu-repo/semantics/article Journal articles 2021 ftccsdartic https://doi.org/10.1029/2021JC017422 2022-01-08T23:54:24Z International audience The future wide-swath satellite altimeters, such as the upcoming Surface Water Ocean Topography (SWOT) mission, will provide instantaneous 2D measurements of sea level down to the spatial scale of O(10 km) for the first time. However, the validity of the geostrophic assumption for estimating surface currents from these instantaneous maps is not known a priori. In this study, we quantify the accuracy of geostrophy for the estimation of surface currents from a knowledge of instantaneous sea level using the hourly snapshots from a tide- and eddy-resolving global numerical simulation. Geostrophic balance is found to be the leading-order balance in frontal regions characterized by large kinetic energy, such as the western boundary currents and the Antarctic Circumpolar Current. Everywhere else, geostrophic approximation ceases to be a useful predictor of ocean velocity, which may result in significant high-frequency contamination of geostrophically computed velocities by fast variability (e.g., inertial and higher). As expected, the validity of geostrophy is shown to improve at low frequencies (typically urn:x-wiley:21699275:media:jgrc24720:jgrc24720-math-0001 0.5 cpd). Global estimates of the horizontal momentum budget reveal that the tropical and mid-latitude regions where geostrophic balance fails are dominated by fast variability and turbulent stress divergence terms rather than higher-order geostrophic terms. These findings indicate that the estimation of velocity from geostrophy applied on SWOT instantaneous sea level maps may be challenging away from energetic areas. Article in Journal/Newspaper Antarc* Antarctic Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Antarctic The Antarctic Journal of Geophysical Research: Oceans 126 10 |