Impact of intensified Indian Ocean winds on mesoscale variability in the Agulhas system.
International audience South of Africa, the Agulhas Current retroflects and a portion of its waters flows into the South Atlantic Ocean1, typically in the form of Agulhas rings2. This flux of warm and salty water from the Indian to the Atlantic Ocean (the Agulhas leakage) is now recognized as a key...
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Online Access: | https://hal.archives-ouvertes.fr/hal-00738939 https://doi.org/10.1038/nclimate1587 |
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ftccsdartic:oai:HAL:hal-00738939v1 2023-05-15T17:35:35+02:00 Impact of intensified Indian Ocean winds on mesoscale variability in the Agulhas system. Backeberg, Björn C. Penven, Pierrick Rouault, Mathieu Nansen-Tutu Centre for Marine Environmental Research University of Cape Town Department of Oceanography Department of Oceanography Cape Town 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) 2012 https://hal.archives-ouvertes.fr/hal-00738939 https://doi.org/10.1038/nclimate1587 en eng HAL CCSD Nature Publishing Group info:eu-repo/semantics/altIdentifier/doi/10.1038/nclimate1587 hal-00738939 https://hal.archives-ouvertes.fr/hal-00738939 doi:10.1038/nclimate1587 ISSN: 1758-678X EISSN: 1758-6798 Nature Climate Change https://hal.archives-ouvertes.fr/hal-00738939 Nature Climate Change, Nature Publishing Group, 2012, 2, pp.608-612. ⟨10.1038/nclimate1587⟩ [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography info:eu-repo/semantics/article Journal articles 2012 ftccsdartic https://doi.org/10.1038/nclimate1587 2021-10-17T01:45:39Z International audience South of Africa, the Agulhas Current retroflects and a portion of its waters flows into the South Atlantic Ocean1, typically in the form of Agulhas rings2. This flux of warm and salty water from the Indian to the Atlantic Ocean (the Agulhas leakage) is now recognized as a key element in global climate3. An Agulhas leakage shutdown has been associated with extreme glacial periods4, whereas a vigorous increase has preceded shifts towards interglacials5. In the absence of a coherent observing system, studies of the Agulhas have relied heavily on ocean models, which have revealed a possible recent increase in Agulhas leakage6, 7, 8. However, owing to the high levels of oceanic turbulence, model solutions of the region are highly sensitive to their numerical choices9, 10, stressing the need for observations to confirm these important model results. Here, using satellite altimetry observations from 1993 to 2009, we show that the mesoscale variability of the Agulhas system, in particular in the Mozambique Channel and south of Madagascar, has intensified. This seems to result from an increased South Equatorial Current driven by enhanced trade winds over the tropical Indian Ocean. Overall, the intensified mesoscale variability of the Agulhas system is reflected in accelerated eddy propagation, in its source regions as well as the retroflection from which eddies propagate into the South Atlantic Ocean. This suggests that the Agulhas leakage may have increased from 1993 to 2009, confirming previous modelling studies that have further implied an increased Agulhas leakage may compensate a deceleration of meridional overturning circulation associated with a freshening of the North Atlantic Ocean6, 11. Article in Journal/Newspaper North Atlantic South Atlantic Ocean Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Indian Nature Climate Change 2 8 608 612 |
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Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
spellingShingle |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography Backeberg, Björn C. Penven, Pierrick Rouault, Mathieu Impact of intensified Indian Ocean winds on mesoscale variability in the Agulhas system. |
topic_facet |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
description |
International audience South of Africa, the Agulhas Current retroflects and a portion of its waters flows into the South Atlantic Ocean1, typically in the form of Agulhas rings2. This flux of warm and salty water from the Indian to the Atlantic Ocean (the Agulhas leakage) is now recognized as a key element in global climate3. An Agulhas leakage shutdown has been associated with extreme glacial periods4, whereas a vigorous increase has preceded shifts towards interglacials5. In the absence of a coherent observing system, studies of the Agulhas have relied heavily on ocean models, which have revealed a possible recent increase in Agulhas leakage6, 7, 8. However, owing to the high levels of oceanic turbulence, model solutions of the region are highly sensitive to their numerical choices9, 10, stressing the need for observations to confirm these important model results. Here, using satellite altimetry observations from 1993 to 2009, we show that the mesoscale variability of the Agulhas system, in particular in the Mozambique Channel and south of Madagascar, has intensified. This seems to result from an increased South Equatorial Current driven by enhanced trade winds over the tropical Indian Ocean. Overall, the intensified mesoscale variability of the Agulhas system is reflected in accelerated eddy propagation, in its source regions as well as the retroflection from which eddies propagate into the South Atlantic Ocean. This suggests that the Agulhas leakage may have increased from 1993 to 2009, confirming previous modelling studies that have further implied an increased Agulhas leakage may compensate a deceleration of meridional overturning circulation associated with a freshening of the North Atlantic Ocean6, 11. |
author2 |
Nansen-Tutu Centre for Marine Environmental Research University of Cape Town Department of Oceanography Department of Oceanography Cape Town 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) |
format |
Article in Journal/Newspaper |
author |
Backeberg, Björn C. Penven, Pierrick Rouault, Mathieu |
author_facet |
Backeberg, Björn C. Penven, Pierrick Rouault, Mathieu |
author_sort |
Backeberg, Björn C. |
title |
Impact of intensified Indian Ocean winds on mesoscale variability in the Agulhas system. |
title_short |
Impact of intensified Indian Ocean winds on mesoscale variability in the Agulhas system. |
title_full |
Impact of intensified Indian Ocean winds on mesoscale variability in the Agulhas system. |
title_fullStr |
Impact of intensified Indian Ocean winds on mesoscale variability in the Agulhas system. |
title_full_unstemmed |
Impact of intensified Indian Ocean winds on mesoscale variability in the Agulhas system. |
title_sort |
impact of intensified indian ocean winds on mesoscale variability in the agulhas system. |
publisher |
HAL CCSD |
publishDate |
2012 |
url |
https://hal.archives-ouvertes.fr/hal-00738939 https://doi.org/10.1038/nclimate1587 |
geographic |
Indian |
geographic_facet |
Indian |
genre |
North Atlantic South Atlantic Ocean |
genre_facet |
North Atlantic South Atlantic Ocean |
op_source |
ISSN: 1758-678X EISSN: 1758-6798 Nature Climate Change https://hal.archives-ouvertes.fr/hal-00738939 Nature Climate Change, Nature Publishing Group, 2012, 2, pp.608-612. ⟨10.1038/nclimate1587⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1038/nclimate1587 hal-00738939 https://hal.archives-ouvertes.fr/hal-00738939 doi:10.1038/nclimate1587 |
op_doi |
https://doi.org/10.1038/nclimate1587 |
container_title |
Nature Climate Change |
container_volume |
2 |
container_issue |
8 |
container_start_page |
608 |
op_container_end_page |
612 |
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1766134785453850624 |