Cold vs. warm water route – sources for the upper limb of the Atlantic Meridional Overturning Circulation revisited in a high-resolution ocean model
International audience The northward flow of the upper limb of the Atlantic Meridional Overturning Circulation (AMOC) is fed by waters entering the South Atlantic from the Indian Ocean mainly via the Agulhas Current (AC) system and by waters entering from the Pacific through Drake Passage (DP), comm...
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Language: | English |
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Online Access: | https://hal.sorbonne-universite.fr/hal-02143879 https://hal.sorbonne-universite.fr/hal-02143879/document https://hal.sorbonne-universite.fr/hal-02143879/file/os-15-489-2019.pdf https://doi.org/10.5194/os-15-489-2019 |
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ftecoleponts:oai:HAL:hal-02143879v1 2024-06-09T07:45:37+00:00 Cold vs. warm water route – sources for the upper limb of the Atlantic Meridional Overturning Circulation revisited in a high-resolution ocean model Rühs, Siren Schwarzkopf, Franziska, U Speich, Sabrina Biastoch, Arne Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR) Laboratoire de Météorologie Dynamique (UMR 8539) (LMD) Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL) 2019 https://hal.sorbonne-universite.fr/hal-02143879 https://hal.sorbonne-universite.fr/hal-02143879/document https://hal.sorbonne-universite.fr/hal-02143879/file/os-15-489-2019.pdf https://doi.org/10.5194/os-15-489-2019 en eng HAL CCSD European Geosciences Union info:eu-repo/semantics/altIdentifier/doi/10.5194/os-15-489-2019 hal-02143879 https://hal.sorbonne-universite.fr/hal-02143879 https://hal.sorbonne-universite.fr/hal-02143879/document https://hal.sorbonne-universite.fr/hal-02143879/file/os-15-489-2019.pdf doi:10.5194/os-15-489-2019 info:eu-repo/semantics/OpenAccess ISSN: 1812-0784 EISSN: 1812-0792 Ocean Science https://hal.sorbonne-universite.fr/hal-02143879 Ocean Science, 2019, 15 (3), pp.489-512. ⟨10.5194/os-15-489-2019⟩ [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography info:eu-repo/semantics/article Journal articles 2019 ftecoleponts https://doi.org/10.5194/os-15-489-2019 2024-05-16T13:09:47Z International audience The northward flow of the upper limb of the Atlantic Meridional Overturning Circulation (AMOC) is fed by waters entering the South Atlantic from the Indian Ocean mainly via the Agulhas Current (AC) system and by waters entering from the Pacific through Drake Passage (DP), commonly referred to as the "warm" and "cold" water routes, respectively. However, there is no final consensus on the relative importance of these two routes for the upper limb's volume transport and thermohaline properties. In this study we revisited the AC and DP contributions by performing La-grangian analyses between the two source regions and the North Brazil Current (NBC) at 6 • S in a realistically forced high-resolution (1/20 •) ocean model. Our results agree with the prevailing conception that the AC contribution is the major source for the upper limb transport of the AMOC in the tropical South Atlantic. However, they also suggest a non-negligible DP contribution of around 40 %, which is substantially higher than estimates from previous Lagrangian studies with coarser-resolution models but now better matches estimates from Lagrangian observations. Moreover, idealized analyses of decadal changes in the DP and AC contributions indicate that the ongoing increase in Agulhas leakage indeed may have induced an increase in the AC contribution to the upper limb of the AMOC in the tropics , while the DP contribution decreased. In terms of ther-mohaline properties, our study highlights the fact that the AC and DP contributions cannot be unambiguously distinguished by their temperature, as the commonly adopted terminology may imply, but rather by their salinity when entering the South Atlantic. During their transit towards the NBC the bulk of DP waters experiences a net density loss through a net warming, whereas the bulk of AC waters experiences a slight net density gain through a net increase in salinity. Notably, these density changes are nearly completely captured by Lagrangian particle trajectories that reach the ... Article in Journal/Newspaper Drake Passage École des Ponts ParisTech: HAL Drake Passage Pacific Indian Ocean Science 15 3 489 512 |
institution |
Open Polar |
collection |
École des Ponts ParisTech: HAL |
op_collection_id |
ftecoleponts |
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 Rühs, Siren Schwarzkopf, Franziska, U Speich, Sabrina Biastoch, Arne Cold vs. warm water route – sources for the upper limb of the Atlantic Meridional Overturning Circulation revisited in a high-resolution ocean model |
topic_facet |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
description |
International audience The northward flow of the upper limb of the Atlantic Meridional Overturning Circulation (AMOC) is fed by waters entering the South Atlantic from the Indian Ocean mainly via the Agulhas Current (AC) system and by waters entering from the Pacific through Drake Passage (DP), commonly referred to as the "warm" and "cold" water routes, respectively. However, there is no final consensus on the relative importance of these two routes for the upper limb's volume transport and thermohaline properties. In this study we revisited the AC and DP contributions by performing La-grangian analyses between the two source regions and the North Brazil Current (NBC) at 6 • S in a realistically forced high-resolution (1/20 •) ocean model. Our results agree with the prevailing conception that the AC contribution is the major source for the upper limb transport of the AMOC in the tropical South Atlantic. However, they also suggest a non-negligible DP contribution of around 40 %, which is substantially higher than estimates from previous Lagrangian studies with coarser-resolution models but now better matches estimates from Lagrangian observations. Moreover, idealized analyses of decadal changes in the DP and AC contributions indicate that the ongoing increase in Agulhas leakage indeed may have induced an increase in the AC contribution to the upper limb of the AMOC in the tropics , while the DP contribution decreased. In terms of ther-mohaline properties, our study highlights the fact that the AC and DP contributions cannot be unambiguously distinguished by their temperature, as the commonly adopted terminology may imply, but rather by their salinity when entering the South Atlantic. During their transit towards the NBC the bulk of DP waters experiences a net density loss through a net warming, whereas the bulk of AC waters experiences a slight net density gain through a net increase in salinity. Notably, these density changes are nearly completely captured by Lagrangian particle trajectories that reach the ... |
author2 |
Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR) Laboratoire de Météorologie Dynamique (UMR 8539) (LMD) Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL) |
format |
Article in Journal/Newspaper |
author |
Rühs, Siren Schwarzkopf, Franziska, U Speich, Sabrina Biastoch, Arne |
author_facet |
Rühs, Siren Schwarzkopf, Franziska, U Speich, Sabrina Biastoch, Arne |
author_sort |
Rühs, Siren |
title |
Cold vs. warm water route – sources for the upper limb of the Atlantic Meridional Overturning Circulation revisited in a high-resolution ocean model |
title_short |
Cold vs. warm water route – sources for the upper limb of the Atlantic Meridional Overturning Circulation revisited in a high-resolution ocean model |
title_full |
Cold vs. warm water route – sources for the upper limb of the Atlantic Meridional Overturning Circulation revisited in a high-resolution ocean model |
title_fullStr |
Cold vs. warm water route – sources for the upper limb of the Atlantic Meridional Overturning Circulation revisited in a high-resolution ocean model |
title_full_unstemmed |
Cold vs. warm water route – sources for the upper limb of the Atlantic Meridional Overturning Circulation revisited in a high-resolution ocean model |
title_sort |
cold vs. warm water route – sources for the upper limb of the atlantic meridional overturning circulation revisited in a high-resolution ocean model |
publisher |
HAL CCSD |
publishDate |
2019 |
url |
https://hal.sorbonne-universite.fr/hal-02143879 https://hal.sorbonne-universite.fr/hal-02143879/document https://hal.sorbonne-universite.fr/hal-02143879/file/os-15-489-2019.pdf https://doi.org/10.5194/os-15-489-2019 |
geographic |
Drake Passage Pacific Indian |
geographic_facet |
Drake Passage Pacific Indian |
genre |
Drake Passage |
genre_facet |
Drake Passage |
op_source |
ISSN: 1812-0784 EISSN: 1812-0792 Ocean Science https://hal.sorbonne-universite.fr/hal-02143879 Ocean Science, 2019, 15 (3), pp.489-512. ⟨10.5194/os-15-489-2019⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/os-15-489-2019 hal-02143879 https://hal.sorbonne-universite.fr/hal-02143879 https://hal.sorbonne-universite.fr/hal-02143879/document https://hal.sorbonne-universite.fr/hal-02143879/file/os-15-489-2019.pdf doi:10.5194/os-15-489-2019 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.5194/os-15-489-2019 |
container_title |
Ocean Science |
container_volume |
15 |
container_issue |
3 |
container_start_page |
489 |
op_container_end_page |
512 |
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1801375082300309504 |