Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate
International audience Sediment cores from the Mediterranean Sea have evidenced several periods of Sapropel deposition, which can be explained by events of anoxic bottom conditions. An explanation for such events calls for a very stratified sea, possibly related with freshwater input through increas...
Published in: | Climate Dynamics |
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Format: | Article in Journal/Newspaper |
Language: | English |
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HAL CCSD
2019
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Online Access: | https://hal.science/hal-02122482 https://hal.science/hal-02122482/document https://hal.science/hal-02122482/file/Draft_Final_HAL.pdf https://doi.org/10.1007/s00382-019-04758-5 |
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Open Polar |
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Université de Nantes: HAL-UNIV-NANTES |
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ftunivnantes |
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English |
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[SDE]Environmental Sciences [SDE.MCG]Environmental Sciences/Global Changes |
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[SDE]Environmental Sciences [SDE.MCG]Environmental Sciences/Global Changes Swingedouw, Didier Colin, Christophe Eynaud, Frédérique Ayache, Mohamed Zaragosi, Sébastien Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate |
topic_facet |
[SDE]Environmental Sciences [SDE.MCG]Environmental Sciences/Global Changes |
description |
International audience Sediment cores from the Mediterranean Sea have evidenced several periods of Sapropel deposition, which can be explained by events of anoxic bottom conditions. An explanation for such events calls for a very stratified sea, possibly related with freshwater input through increased precipitations and runoff discharges. It has been suggested that such a stratified Mediterranean Sea may in turn weaken the Atlantic meridional overturning circulation (AMOC) through changes in the Mediterranean overflow water (MOW). Nevertheless, models used to establish this result were relatively simple and the mechanisms leading to such an impact remained elusive. To improve on those previous studies, we analyse the impact of different freshwater releases with rates of 0.2, 0.1, 0.05 and 0.02 Sv (1 Sv=10 6 m 3 /s) in the Mediterranean Sea using the IPSL-CM5A-LR model in a few multi-centennial simulations. We focus the analysis on the impact of a decrease in the Mediterranean overflow water (MOW) on the large-scale Atlantic circulation. We find a consistent change in horizontal currents in the upper Atlantic Ocean in all simulations in the first century, with a large enhancement of the northward current west of Rockall in the northeast Atlantic. Concerning the AMOC response, we identify three different processes that impact its fate. The first is related to changes in geostrophic currents at depth induced by the disappearance of the MOW, which tends to weaken the AMOC. On the contrary, the second enhances the AMOC and is associated with the increase in northward currents in the horizontal upper circulation. The last process is due to the spread of surface freshwater anomalies out of the Mediterranean Sea that freshens the North Atlantic convection sites and weakens the AMOC. Depending on the rate of the freshwater release, the strength and balance of these three processes are different. For rates larger than 0.05 Sv, we observe a strong reduction of the AMOC, while for lower rates, we notice an enhancement in ... |
author2 |
Environnements et Paléoenvironnements OCéaniques (EPOC) Observatoire aquitain des sciences de l'univers (OASU) Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS) Géosciences Paris Sud (GEOPS) Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS) Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE) Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Swingedouw, Didier Colin, Christophe Eynaud, Frédérique Ayache, Mohamed Zaragosi, Sébastien |
author_facet |
Swingedouw, Didier Colin, Christophe Eynaud, Frédérique Ayache, Mohamed Zaragosi, Sébastien |
author_sort |
Swingedouw, Didier |
title |
Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate |
title_short |
Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate |
title_full |
Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate |
title_fullStr |
Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate |
title_full_unstemmed |
Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate |
title_sort |
impact of freshwater release in the mediterranean sea on the north atlantic climate |
publisher |
HAL CCSD |
publishDate |
2019 |
url |
https://hal.science/hal-02122482 https://hal.science/hal-02122482/document https://hal.science/hal-02122482/file/Draft_Final_HAL.pdf https://doi.org/10.1007/s00382-019-04758-5 |
genre |
North Atlantic Northeast Atlantic |
genre_facet |
North Atlantic Northeast Atlantic |
op_source |
ISSN: 0930-7575 EISSN: 1432-0894 Climate Dynamics https://hal.science/hal-02122482 Climate Dynamics, 2019, 53 ((7-8):), pp.3893-3915 (IF 4,708). ⟨10.1007/s00382-019-04758-5⟩ |
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info:eu-repo/semantics/altIdentifier/doi/10.1007/s00382-019-04758-5 hal-02122482 https://hal.science/hal-02122482 https://hal.science/hal-02122482/document https://hal.science/hal-02122482/file/Draft_Final_HAL.pdf doi:10.1007/s00382-019-04758-5 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1007/s00382-019-04758-5 |
container_title |
Climate Dynamics |
container_volume |
53 |
container_issue |
7-8 |
container_start_page |
3893 |
op_container_end_page |
3915 |
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1766130829570867200 |
spelling |
ftunivnantes:oai:HAL:hal-02122482v1 2023-05-15T17:32:37+02:00 Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate Swingedouw, Didier Colin, Christophe Eynaud, Frédérique Ayache, Mohamed Zaragosi, Sébastien Environnements et Paléoenvironnements OCéaniques (EPOC) Observatoire aquitain des sciences de l'univers (OASU) Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS) Géosciences Paris Sud (GEOPS) Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS) Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE) Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS) 2019-10-29 https://hal.science/hal-02122482 https://hal.science/hal-02122482/document https://hal.science/hal-02122482/file/Draft_Final_HAL.pdf https://doi.org/10.1007/s00382-019-04758-5 en eng HAL CCSD Springer Verlag info:eu-repo/semantics/altIdentifier/doi/10.1007/s00382-019-04758-5 hal-02122482 https://hal.science/hal-02122482 https://hal.science/hal-02122482/document https://hal.science/hal-02122482/file/Draft_Final_HAL.pdf doi:10.1007/s00382-019-04758-5 info:eu-repo/semantics/OpenAccess ISSN: 0930-7575 EISSN: 1432-0894 Climate Dynamics https://hal.science/hal-02122482 Climate Dynamics, 2019, 53 ((7-8):), pp.3893-3915 (IF 4,708). ⟨10.1007/s00382-019-04758-5⟩ [SDE]Environmental Sciences [SDE.MCG]Environmental Sciences/Global Changes info:eu-repo/semantics/article Journal articles 2019 ftunivnantes https://doi.org/10.1007/s00382-019-04758-5 2023-02-08T07:41:35Z International audience Sediment cores from the Mediterranean Sea have evidenced several periods of Sapropel deposition, which can be explained by events of anoxic bottom conditions. An explanation for such events calls for a very stratified sea, possibly related with freshwater input through increased precipitations and runoff discharges. It has been suggested that such a stratified Mediterranean Sea may in turn weaken the Atlantic meridional overturning circulation (AMOC) through changes in the Mediterranean overflow water (MOW). Nevertheless, models used to establish this result were relatively simple and the mechanisms leading to such an impact remained elusive. To improve on those previous studies, we analyse the impact of different freshwater releases with rates of 0.2, 0.1, 0.05 and 0.02 Sv (1 Sv=10 6 m 3 /s) in the Mediterranean Sea using the IPSL-CM5A-LR model in a few multi-centennial simulations. We focus the analysis on the impact of a decrease in the Mediterranean overflow water (MOW) on the large-scale Atlantic circulation. We find a consistent change in horizontal currents in the upper Atlantic Ocean in all simulations in the first century, with a large enhancement of the northward current west of Rockall in the northeast Atlantic. Concerning the AMOC response, we identify three different processes that impact its fate. The first is related to changes in geostrophic currents at depth induced by the disappearance of the MOW, which tends to weaken the AMOC. On the contrary, the second enhances the AMOC and is associated with the increase in northward currents in the horizontal upper circulation. The last process is due to the spread of surface freshwater anomalies out of the Mediterranean Sea that freshens the North Atlantic convection sites and weakens the AMOC. Depending on the rate of the freshwater release, the strength and balance of these three processes are different. For rates larger than 0.05 Sv, we observe a strong reduction of the AMOC, while for lower rates, we notice an enhancement in ... Article in Journal/Newspaper North Atlantic Northeast Atlantic Université de Nantes: HAL-UNIV-NANTES Climate Dynamics 53 7-8 3893 3915 |