Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade
Using an Argo dataset and the ECCOv4 reanalysis, a volume budget was performed to address the main mechanisms driving the volume change of the interior water masses in the Southern Hemisphere oceans between 2006 and 2015. The subduction rates and the isopycnal and diapycnal water-mass transformation...
Published in: | Journal of Physical Oceanography |
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Language: | English |
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ftccsdartic:oai:HAL:hal-04202522v1 2023-12-17T10:21:00+01:00 Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade Portela, Esther Kolodziejczyk, Nicolas Maes, Christophe Thierry, Virginie Laboratoire d'Océanographie Physique et Spatiale (LOPS) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS) 2020-02 https://hal.science/hal-04202522 https://hal.science/hal-04202522/document https://hal.science/hal-04202522/file/phoc-jpo-d-19-0128.1.pdf https://doi.org/10.1175/JPO-D-19-0128.1 en eng HAL CCSD American Meteorological Society info:eu-repo/semantics/altIdentifier/doi/10.1175/JPO-D-19-0128.1 hal-04202522 https://hal.science/hal-04202522 https://hal.science/hal-04202522/document https://hal.science/hal-04202522/file/phoc-jpo-d-19-0128.1.pdf doi:10.1175/JPO-D-19-0128.1 IRD: fdi:010077860 info:eu-repo/semantics/OpenAccess ISSN: 0022-3670 EISSN: 1520-0485 Journal of Physical Oceanography https://hal.science/hal-04202522 Journal of Physical Oceanography, 2020, 50 (2), pp.361-381. ⟨10.1175/JPO-D-19-0128.1⟩ [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2020 ftccsdartic https://doi.org/10.1175/JPO-D-19-0128.1 2023-11-18T23:42:50Z Using an Argo dataset and the ECCOv4 reanalysis, a volume budget was performed to address the main mechanisms driving the volume change of the interior water masses in the Southern Hemisphere oceans between 2006 and 2015. The subduction rates and the isopycnal and diapycnal water-mass transformation were estimated in a density-spiciness (sigma-tau) framework. Spiciness, defined as thermohaline variations along isopycnals, was added to the potential density coordinates to discriminate between water masses spreading on isopycnal layers. The main positive volume trends were found to be associated with the Subantarctic Mode Waters (SAMW) in the South Pacific and South Indian Ocean basins, revealing a lightening of the upper waters in the Southern Hemisphere. The SAMW exhibits a two-layer density structure in which subduction and diapycnal transformation from the lower to the upper layers accounted for most of the upper-layer volume gain and lower-layer volume loss, respectively. The Antarctic Intermediate Waters, defined here between the 27.2 and 27.5 kg m(-3) isopycnals, showed the strongest negative volume trends. This volume loss can be explained by their negative isopyncal transformation southward of the Antarctic Circumpolar Current into the fresher and colder Antarctic Winter Waters (AAWW) and northward into spicier tropical/subtropical Intermediate Waters. The AAWW is destroyed by obduction back into the mixed layer so that its net volume change remains nearly zero. The proposed mechanisms to explain the transformation within the Intermediate Waters are discussed in the context of Southern Ocean dynamics. The sigma-tau decomposition provided new insight on the spatial and temporal water-mass variability and driving mechanisms over the last decade. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Antarctic Southern Ocean The Antarctic Pacific Indian Journal of Physical Oceanography 50 2 361 381 |
institution |
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]Sciences of the Universe [physics] |
spellingShingle |
[SDU]Sciences of the Universe [physics] Portela, Esther Kolodziejczyk, Nicolas Maes, Christophe Thierry, Virginie Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade |
topic_facet |
[SDU]Sciences of the Universe [physics] |
description |
Using an Argo dataset and the ECCOv4 reanalysis, a volume budget was performed to address the main mechanisms driving the volume change of the interior water masses in the Southern Hemisphere oceans between 2006 and 2015. The subduction rates and the isopycnal and diapycnal water-mass transformation were estimated in a density-spiciness (sigma-tau) framework. Spiciness, defined as thermohaline variations along isopycnals, was added to the potential density coordinates to discriminate between water masses spreading on isopycnal layers. The main positive volume trends were found to be associated with the Subantarctic Mode Waters (SAMW) in the South Pacific and South Indian Ocean basins, revealing a lightening of the upper waters in the Southern Hemisphere. The SAMW exhibits a two-layer density structure in which subduction and diapycnal transformation from the lower to the upper layers accounted for most of the upper-layer volume gain and lower-layer volume loss, respectively. The Antarctic Intermediate Waters, defined here between the 27.2 and 27.5 kg m(-3) isopycnals, showed the strongest negative volume trends. This volume loss can be explained by their negative isopyncal transformation southward of the Antarctic Circumpolar Current into the fresher and colder Antarctic Winter Waters (AAWW) and northward into spicier tropical/subtropical Intermediate Waters. The AAWW is destroyed by obduction back into the mixed layer so that its net volume change remains nearly zero. The proposed mechanisms to explain the transformation within the Intermediate Waters are discussed in the context of Southern Ocean dynamics. The sigma-tau decomposition provided new insight on the spatial and temporal water-mass variability and driving mechanisms over the last decade. |
author2 |
Laboratoire d'Océanographie Physique et Spatiale (LOPS) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Portela, Esther Kolodziejczyk, Nicolas Maes, Christophe Thierry, Virginie |
author_facet |
Portela, Esther Kolodziejczyk, Nicolas Maes, Christophe Thierry, Virginie |
author_sort |
Portela, Esther |
title |
Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade |
title_short |
Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade |
title_full |
Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade |
title_fullStr |
Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade |
title_full_unstemmed |
Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade |
title_sort |
interior water-mass variability in the southern hemisphere oceans during the last decade |
publisher |
HAL CCSD |
publishDate |
2020 |
url |
https://hal.science/hal-04202522 https://hal.science/hal-04202522/document https://hal.science/hal-04202522/file/phoc-jpo-d-19-0128.1.pdf https://doi.org/10.1175/JPO-D-19-0128.1 |
geographic |
Antarctic Southern Ocean The Antarctic Pacific Indian |
geographic_facet |
Antarctic Southern Ocean The Antarctic Pacific Indian |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
ISSN: 0022-3670 EISSN: 1520-0485 Journal of Physical Oceanography https://hal.science/hal-04202522 Journal of Physical Oceanography, 2020, 50 (2), pp.361-381. ⟨10.1175/JPO-D-19-0128.1⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1175/JPO-D-19-0128.1 hal-04202522 https://hal.science/hal-04202522 https://hal.science/hal-04202522/document https://hal.science/hal-04202522/file/phoc-jpo-d-19-0128.1.pdf doi:10.1175/JPO-D-19-0128.1 IRD: fdi:010077860 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1175/JPO-D-19-0128.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
50 |
container_issue |
2 |
container_start_page |
361 |
op_container_end_page |
381 |
_version_ |
1785528389420974080 |