Variability of the ocean circulation in the North-Atlantic in response to atmospheric weather regimes
The aim of the PhD is to investigate the impacts of the large-Scale atmospheric variability on the North- Atlantic ocean circulation. This question has already been addressed in a large number of studies, in which the atmospheric variability is decomposed into modes of variability, determined by dec...
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Online Access: | https://theses.hal.science/tel-01124247 https://theses.hal.science/tel-01124247/document https://theses.hal.science/tel-01124247/file/2013BRES0064.pdf |
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ftunivbrest:oai:HAL:tel-01124247v1 2023-12-17T10:45:57+01:00 Variability of the ocean circulation in the North-Atlantic in response to atmospheric weather regimes Variabilité de la circulation océanique en Atlantique Nord en réponse aux régimes de temps atmosphériques Barrier, Nicolas Laboratoire de physique des océans (LPO) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS) Université de Bretagne occidentale - Brest Anne-Marie Treguier 2013-11-25 https://theses.hal.science/tel-01124247 https://theses.hal.science/tel-01124247/document https://theses.hal.science/tel-01124247/file/2013BRES0064.pdf en eng HAL CCSD NNT: 2013BRES0064 tel-01124247 https://theses.hal.science/tel-01124247 https://theses.hal.science/tel-01124247/document https://theses.hal.science/tel-01124247/file/2013BRES0064.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-01124247 Earth Sciences. Université de Bretagne occidentale - Brest, 2013. English. ⟨NNT : 2013BRES0064⟩ Weather regimes Meridional overturning circulation North Atlantic Gyres North Atlantic Oscillation Modes of variability Heat content Nordic seas Régime de temps Circulation thermohaline Atlantique Nord Oscillation Nord Atlantique Modes de variabilité Contenus de chaleur Mers nordiques [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/doctoralThesis Theses 2013 ftunivbrest 2023-11-21T23:43:42Z The aim of the PhD is to investigate the impacts of the large-Scale atmospheric variability on the North- Atlantic ocean circulation. This question has already been addressed in a large number of studies, in which the atmospheric variability is decomposed into modes of variability, determined by decomposing sea-Level pressure anomalies into Empirical Orthogonal Function (EOFs). These modes of variability are the North-Atlantic Oscillation (NAO), the East-Atlantic Pattern (EAP) and the Scandinavian Pattern (SCAN). EOF decomposition assumes that the modes are orthogonal and symmetric. The latter assumption, however, has been shown to be inadequate for the NAO. Hence, a different framework is used in this study to assess the atmospheric variability, the so-Called weather regimes. These are large-Scale, recurrent and quasi-Stationary atmospheric patterns that have been shown to capture well the interannual and decadal variability of atmospheric forcing to the ocean. Furthermore, they allow to separate the spatial patterns of the positive and negative NAO phases. Hence, these weather regimes are a promising alternative to modes of variability in the study of the ocean response to atmospheric variability. Using observations and numerical models (realistic or in idealised settings), we have shown that the Atlantic Ridge (AR), NAO− and NAO+ regimes drive a fast (monthly to interannual) wind-Driven response of the subtropical and subpolar gyres (topographic Sverdrup balance) and of the meridional overturning circulation (MOC, driven by Ekman transport anomalies). At decadal timescales, the subpolar gyre strengthens for persistent NAO+ and Scandinavian Blocking (BLK) conditions via baroclinic adjustment to buoyancy fluxes and slackens for persistent AR conditions via baroclinic adjustment to wind-Stress curl anomalies. The latter mechanism also accounts for the strengthening of the subtropical gyre for persistent NAO+ conditions and its weakening for persistent AR conditions. The gyres response to persistent NAO− ... Doctoral or Postdoctoral Thesis Nordic Seas North Atlantic North Atlantic oscillation Université de Bretagne Occidentale: HAL Curl ENVELOPE(-63.071,-63.071,-70.797,-70.797) |
institution |
Open Polar |
collection |
Université de Bretagne Occidentale: HAL |
op_collection_id |
ftunivbrest |
language |
English |
topic |
Weather regimes Meridional overturning circulation North Atlantic Gyres North Atlantic Oscillation Modes of variability Heat content Nordic seas Régime de temps Circulation thermohaline Atlantique Nord Oscillation Nord Atlantique Modes de variabilité Contenus de chaleur Mers nordiques [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
Weather regimes Meridional overturning circulation North Atlantic Gyres North Atlantic Oscillation Modes of variability Heat content Nordic seas Régime de temps Circulation thermohaline Atlantique Nord Oscillation Nord Atlantique Modes de variabilité Contenus de chaleur Mers nordiques [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Barrier, Nicolas Variability of the ocean circulation in the North-Atlantic in response to atmospheric weather regimes |
topic_facet |
Weather regimes Meridional overturning circulation North Atlantic Gyres North Atlantic Oscillation Modes of variability Heat content Nordic seas Régime de temps Circulation thermohaline Atlantique Nord Oscillation Nord Atlantique Modes de variabilité Contenus de chaleur Mers nordiques [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
The aim of the PhD is to investigate the impacts of the large-Scale atmospheric variability on the North- Atlantic ocean circulation. This question has already been addressed in a large number of studies, in which the atmospheric variability is decomposed into modes of variability, determined by decomposing sea-Level pressure anomalies into Empirical Orthogonal Function (EOFs). These modes of variability are the North-Atlantic Oscillation (NAO), the East-Atlantic Pattern (EAP) and the Scandinavian Pattern (SCAN). EOF decomposition assumes that the modes are orthogonal and symmetric. The latter assumption, however, has been shown to be inadequate for the NAO. Hence, a different framework is used in this study to assess the atmospheric variability, the so-Called weather regimes. These are large-Scale, recurrent and quasi-Stationary atmospheric patterns that have been shown to capture well the interannual and decadal variability of atmospheric forcing to the ocean. Furthermore, they allow to separate the spatial patterns of the positive and negative NAO phases. Hence, these weather regimes are a promising alternative to modes of variability in the study of the ocean response to atmospheric variability. Using observations and numerical models (realistic or in idealised settings), we have shown that the Atlantic Ridge (AR), NAO− and NAO+ regimes drive a fast (monthly to interannual) wind-Driven response of the subtropical and subpolar gyres (topographic Sverdrup balance) and of the meridional overturning circulation (MOC, driven by Ekman transport anomalies). At decadal timescales, the subpolar gyre strengthens for persistent NAO+ and Scandinavian Blocking (BLK) conditions via baroclinic adjustment to buoyancy fluxes and slackens for persistent AR conditions via baroclinic adjustment to wind-Stress curl anomalies. The latter mechanism also accounts for the strengthening of the subtropical gyre for persistent NAO+ conditions and its weakening for persistent AR conditions. The gyres response to persistent NAO− ... |
author2 |
Laboratoire de physique des océans (LPO) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS) Université de Bretagne occidentale - Brest Anne-Marie Treguier |
format |
Doctoral or Postdoctoral Thesis |
author |
Barrier, Nicolas |
author_facet |
Barrier, Nicolas |
author_sort |
Barrier, Nicolas |
title |
Variability of the ocean circulation in the North-Atlantic in response to atmospheric weather regimes |
title_short |
Variability of the ocean circulation in the North-Atlantic in response to atmospheric weather regimes |
title_full |
Variability of the ocean circulation in the North-Atlantic in response to atmospheric weather regimes |
title_fullStr |
Variability of the ocean circulation in the North-Atlantic in response to atmospheric weather regimes |
title_full_unstemmed |
Variability of the ocean circulation in the North-Atlantic in response to atmospheric weather regimes |
title_sort |
variability of the ocean circulation in the north-atlantic in response to atmospheric weather regimes |
publisher |
HAL CCSD |
publishDate |
2013 |
url |
https://theses.hal.science/tel-01124247 https://theses.hal.science/tel-01124247/document https://theses.hal.science/tel-01124247/file/2013BRES0064.pdf |
long_lat |
ENVELOPE(-63.071,-63.071,-70.797,-70.797) |
geographic |
Curl |
geographic_facet |
Curl |
genre |
Nordic Seas North Atlantic North Atlantic oscillation |
genre_facet |
Nordic Seas North Atlantic North Atlantic oscillation |
op_source |
https://theses.hal.science/tel-01124247 Earth Sciences. Université de Bretagne occidentale - Brest, 2013. English. ⟨NNT : 2013BRES0064⟩ |
op_relation |
NNT: 2013BRES0064 tel-01124247 https://theses.hal.science/tel-01124247 https://theses.hal.science/tel-01124247/document https://theses.hal.science/tel-01124247/file/2013BRES0064.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1785569276631973888 |