Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods
The inflow of relatively warm and salty water from the Indian Ocean into the South Atlantic via Agulhas leakage is important for the global overturning circulation and the global climate. In this study, we analyse the robustness of Agulhas leakage estimates as well as the thermohaline property modif...
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Copernicus Publications (EGU)
2021
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ftoceanrep:oai:oceanrep.geomar.de:52285 2024-02-11T10:08:32+01:00 Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods Schmidt, Christina Schwarzkopf, Franziska U. Rühs, Siren Biastoch, Arne 2021-08-16 text https://oceanrep.geomar.de/id/eprint/52285/ https://oceanrep.geomar.de/id/eprint/52285/7/os-17-1067-2021.pdf https://doi.org/10.5194/os-17-1067-2021 en eng Copernicus Publications (EGU) https://oceanrep.geomar.de/id/eprint/52285/7/os-17-1067-2021.pdf Schmidt, C. , Schwarzkopf, F. U. , Rühs, S. and Biastoch, A. (2021) Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods. Open Access Ocean Science, 17 . pp. 1067-1080. DOI 10.5194/os-17-1067-2021 <https://doi.org/10.5194/os-17-1067-2021>. doi:10.5194/os-17-1067-2021 cc_by_4.0 info:eu-repo/semantics/openAccess Article PeerReviewed info:eu-repo/semantics/article 2021 ftoceanrep https://doi.org/10.5194/os-17-1067-2021 2024-01-15T00:23:13Z The inflow of relatively warm and salty water from the Indian Ocean into the South Atlantic via Agulhas leakage is important for the global overturning circulation and the global climate. In this study, we analyse the robustness of Agulhas leakage estimates as well as the thermohaline property modifications of Agulhas leakage south of Africa. Lagrangian experiments with both the newly developed tool Parcels and the well established tool Ariane were performed to simulate Agulhas leakage in the eddy-rich ocean–sea-ice model INALT20 (1/20∘ horizontal resolution) forced by the JRA55-do atmospheric boundary conditions. The average transport, its variability, trend and the transit time from the Agulhas Current to the Cape Basin of Agulhas leakage is simulated comparably with both Lagrangian tools, emphasizing the robustness of our method. Different designs of the Lagrangian experiment alter in particular the total transport of Agulhas leakage by up to 2 Sv, but the variability and trend of the transport are similar across these estimates. During the transit from the Agulhas Current at 32∘ S to the Cape Basin, a cooling and freshening of Agulhas leakage waters occurs especially at the location of the Agulhas Retroflection, resulting in a density increase as the thermal effect dominates. Beyond the strong air–sea exchange around South Africa, Agulhas leakage warms and salinifies the water masses below the thermocline in the South Atlantic. Article in Journal/Newspaper Sea ice OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Indian Ocean Science 17 4 1067 1080 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
The inflow of relatively warm and salty water from the Indian Ocean into the South Atlantic via Agulhas leakage is important for the global overturning circulation and the global climate. In this study, we analyse the robustness of Agulhas leakage estimates as well as the thermohaline property modifications of Agulhas leakage south of Africa. Lagrangian experiments with both the newly developed tool Parcels and the well established tool Ariane were performed to simulate Agulhas leakage in the eddy-rich ocean–sea-ice model INALT20 (1/20∘ horizontal resolution) forced by the JRA55-do atmospheric boundary conditions. The average transport, its variability, trend and the transit time from the Agulhas Current to the Cape Basin of Agulhas leakage is simulated comparably with both Lagrangian tools, emphasizing the robustness of our method. Different designs of the Lagrangian experiment alter in particular the total transport of Agulhas leakage by up to 2 Sv, but the variability and trend of the transport are similar across these estimates. During the transit from the Agulhas Current at 32∘ S to the Cape Basin, a cooling and freshening of Agulhas leakage waters occurs especially at the location of the Agulhas Retroflection, resulting in a density increase as the thermal effect dominates. Beyond the strong air–sea exchange around South Africa, Agulhas leakage warms and salinifies the water masses below the thermocline in the South Atlantic. |
format |
Article in Journal/Newspaper |
author |
Schmidt, Christina Schwarzkopf, Franziska U. Rühs, Siren Biastoch, Arne |
spellingShingle |
Schmidt, Christina Schwarzkopf, Franziska U. Rühs, Siren Biastoch, Arne Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods |
author_facet |
Schmidt, Christina Schwarzkopf, Franziska U. Rühs, Siren Biastoch, Arne |
author_sort |
Schmidt, Christina |
title |
Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods |
title_short |
Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods |
title_full |
Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods |
title_fullStr |
Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods |
title_full_unstemmed |
Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods |
title_sort |
characteristics and robustness of agulhas leakage estimates: an inter-comparison study of lagrangian methods |
publisher |
Copernicus Publications (EGU) |
publishDate |
2021 |
url |
https://oceanrep.geomar.de/id/eprint/52285/ https://oceanrep.geomar.de/id/eprint/52285/7/os-17-1067-2021.pdf https://doi.org/10.5194/os-17-1067-2021 |
geographic |
Indian |
geographic_facet |
Indian |
genre |
Sea ice |
genre_facet |
Sea ice |
op_relation |
https://oceanrep.geomar.de/id/eprint/52285/7/os-17-1067-2021.pdf Schmidt, C. , Schwarzkopf, F. U. , Rühs, S. and Biastoch, A. (2021) Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods. Open Access Ocean Science, 17 . pp. 1067-1080. DOI 10.5194/os-17-1067-2021 <https://doi.org/10.5194/os-17-1067-2021>. doi:10.5194/os-17-1067-2021 |
op_rights |
cc_by_4.0 info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/os-17-1067-2021 |
container_title |
Ocean Science |
container_volume |
17 |
container_issue |
4 |
container_start_page |
1067 |
op_container_end_page |
1080 |
_version_ |
1790607917321289728 |