Les eaux modales de l'Océan Austral
Subantarctic mode water (SAMW) are formed in the Southern Ocean in the deep winter mixed layers north of the Subantarctic front. They influence the climate at interannual and decadal scales and play a fundamental role in the ventilation of Southern Hemisphere thermocline. We study the details of SAM...
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Language: | French |
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2007
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Online Access: | https://theses.hal.science/tel-00193791 https://theses.hal.science/tel-00193791/document https://theses.hal.science/tel-00193791/file/merged.pdf |
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ftinsu:oai:HAL:tel-00193791v1 2023-12-17T10:50:24+01:00 Les eaux modales de l'Océan Austral Sallée, Jean-Baptiste Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS) Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP) Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS) Université Paul Sabatier - Toulouse III Rosemary Morrow 2007-11-05 https://theses.hal.science/tel-00193791 https://theses.hal.science/tel-00193791/document https://theses.hal.science/tel-00193791/file/merged.pdf fr fre HAL CCSD tel-00193791 https://theses.hal.science/tel-00193791 https://theses.hal.science/tel-00193791/document https://theses.hal.science/tel-00193791/file/merged.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-00193791 Océan, Atmosphère. Université Paul Sabatier - Toulouse III, 2007. Français. ⟨NNT : ⟩ Ocean Subantarctic mode water Diffusion Océan Austral Eaux modales Tourbillons Fronts Couche de mélange [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/doctoralThesis Theses 2007 ftinsu 2023-11-22T17:46:37Z Subantarctic mode water (SAMW) are formed in the Southern Ocean in the deep winter mixed layers north of the Subantarctic front. They influence the climate at interannual and decadal scales and play a fundamental role in the ventilation of Southern Hemisphere thermocline. We study the details of SAMW formation using the recent deployment of ARGO profiling floats and GDP surface drifters, which provide an excellent space-time coverage of the Southern Ocean upper ocean processes. Since the beginning of the ARGO international program, the number of vertical hydrographic profiles in the Southern Ocean have increased considerably so that nowadays we have a comparable number of profiles to decades of hydrographic ship data. Based on this dataset, we found that the dominant forcing for SAMW formation in winter in the Southern Indian Ocean was due to air-sea and Ekman fluxes. We found a rapid transition to thicker surface mixed layers in the central South Indian Ocean, at about 70°, associated with a reversal of the horizontal eddy heat diffusion in the surface layer and the meridional expansion of the ACC as it rounds the Kerguelen Plateau. These effects are ultimately related to the bathymetry of the region, leading to the seat of formation in the region southwest of Australia. SAMW formation is tightly linked to the Southern Ocean dynamics and position of the main polar fronts. A second study concerned the ACC circulation and frontal variability. In this study we mixed in-situ and altimeter data to monitor the position of the two main fronts of the ACC during the period 1993-2005. Then, we related their movements to the two main atmospheric climate modes of the Southern Hemisphere, the Southern Annular Mode (SAM) and the El-Nino Southern Oscillation (ENSO). We found that although the fronts are steered by the bathymetry, which sets their mean pathway at first order, in flat-bottom areas the fronts are subject to large meandering due to mesoscale activity and atmospheric forcing. In parallel, we developed a new ... Doctoral or Postdoctoral Thesis Southern Ocean Institut national des sciences de l'Univers: HAL-INSU Austral Indian Kerguelen Southern Ocean Tourbillons ENVELOPE(139.951,139.951,-66.669,-66.669) |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
French |
topic |
Ocean Subantarctic mode water Diffusion Océan Austral Eaux modales Tourbillons Fronts Couche de mélange [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
Ocean Subantarctic mode water Diffusion Océan Austral Eaux modales Tourbillons Fronts Couche de mélange [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Sallée, Jean-Baptiste Les eaux modales de l'Océan Austral |
topic_facet |
Ocean Subantarctic mode water Diffusion Océan Austral Eaux modales Tourbillons Fronts Couche de mélange [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
Subantarctic mode water (SAMW) are formed in the Southern Ocean in the deep winter mixed layers north of the Subantarctic front. They influence the climate at interannual and decadal scales and play a fundamental role in the ventilation of Southern Hemisphere thermocline. We study the details of SAMW formation using the recent deployment of ARGO profiling floats and GDP surface drifters, which provide an excellent space-time coverage of the Southern Ocean upper ocean processes. Since the beginning of the ARGO international program, the number of vertical hydrographic profiles in the Southern Ocean have increased considerably so that nowadays we have a comparable number of profiles to decades of hydrographic ship data. Based on this dataset, we found that the dominant forcing for SAMW formation in winter in the Southern Indian Ocean was due to air-sea and Ekman fluxes. We found a rapid transition to thicker surface mixed layers in the central South Indian Ocean, at about 70°, associated with a reversal of the horizontal eddy heat diffusion in the surface layer and the meridional expansion of the ACC as it rounds the Kerguelen Plateau. These effects are ultimately related to the bathymetry of the region, leading to the seat of formation in the region southwest of Australia. SAMW formation is tightly linked to the Southern Ocean dynamics and position of the main polar fronts. A second study concerned the ACC circulation and frontal variability. In this study we mixed in-situ and altimeter data to monitor the position of the two main fronts of the ACC during the period 1993-2005. Then, we related their movements to the two main atmospheric climate modes of the Southern Hemisphere, the Southern Annular Mode (SAM) and the El-Nino Southern Oscillation (ENSO). We found that although the fronts are steered by the bathymetry, which sets their mean pathway at first order, in flat-bottom areas the fronts are subject to large meandering due to mesoscale activity and atmospheric forcing. In parallel, we developed a new ... |
author2 |
Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS) Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP) Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS) Université Paul Sabatier - Toulouse III Rosemary Morrow |
format |
Doctoral or Postdoctoral Thesis |
author |
Sallée, Jean-Baptiste |
author_facet |
Sallée, Jean-Baptiste |
author_sort |
Sallée, Jean-Baptiste |
title |
Les eaux modales de l'Océan Austral |
title_short |
Les eaux modales de l'Océan Austral |
title_full |
Les eaux modales de l'Océan Austral |
title_fullStr |
Les eaux modales de l'Océan Austral |
title_full_unstemmed |
Les eaux modales de l'Océan Austral |
title_sort |
les eaux modales de l'océan austral |
publisher |
HAL CCSD |
publishDate |
2007 |
url |
https://theses.hal.science/tel-00193791 https://theses.hal.science/tel-00193791/document https://theses.hal.science/tel-00193791/file/merged.pdf |
long_lat |
ENVELOPE(139.951,139.951,-66.669,-66.669) |
geographic |
Austral Indian Kerguelen Southern Ocean Tourbillons |
geographic_facet |
Austral Indian Kerguelen Southern Ocean Tourbillons |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
https://theses.hal.science/tel-00193791 Océan, Atmosphère. Université Paul Sabatier - Toulouse III, 2007. Français. ⟨NNT : ⟩ |
op_relation |
tel-00193791 https://theses.hal.science/tel-00193791 https://theses.hal.science/tel-00193791/document https://theses.hal.science/tel-00193791/file/merged.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1785575212224348160 |