Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water
International audience In the North Atlantic subtropical gyre, the Eighteen Degree Water (EDW) is a voluminous heat reservoir, submerged under a seasonal pycnocline that can be progressively removed through the winter, allowing EDW ventilation in the early spring. We target the EDW formation extreme...
Published in: | Journal of Geophysical Research: Oceans |
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Online Access: | https://hal.science/hal-03814771 https://hal.science/hal-03814771/document https://hal.science/hal-03814771/file/90674.pdf https://doi.org/10.1029/2021jc017696 |
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ftccsdartic:oai:HAL:hal-03814771v1 2023-12-17T10:46:28+01:00 Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water Li, Ke Maze, Guillaume Mercier, Herlé 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) 2022 https://hal.science/hal-03814771 https://hal.science/hal-03814771/document https://hal.science/hal-03814771/file/90674.pdf https://doi.org/10.1029/2021jc017696 en eng HAL CCSD Wiley-Blackwell info:eu-repo/semantics/altIdentifier/doi/10.1029/2021jc017696 hal-03814771 https://hal.science/hal-03814771 https://hal.science/hal-03814771/document https://hal.science/hal-03814771/file/90674.pdf doi:10.1029/2021jc017696 info:eu-repo/semantics/OpenAccess ISSN: 2169-9275 EISSN: 2169-9291 Journal of Geophysical Research. Oceans https://hal.science/hal-03814771 Journal of Geophysical Research. Oceans, 2022, 127 (1), pp.e2021JC017696. ⟨10.1029/2021jc017696⟩ [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography info:eu-repo/semantics/article Journal articles 2022 ftccsdartic https://doi.org/10.1029/2021jc017696 2023-11-19T00:02:33Z International audience In the North Atlantic subtropical gyre, the Eighteen Degree Water (EDW) is a voluminous heat reservoir, submerged under a seasonal pycnocline that can be progressively removed through the winter, allowing EDW ventilation in the early spring. We target the EDW formation extremes, namely 2004–2005, 2009–2010, and 2012–2013 for the strong years, and 2007–2008, 2008–2009, 2011–2012, and 2013–2014 for the weak years. We employ gridded hydrographic datasets mainly measured by Argo floats over the last 20 years, and provide a synthetic study on the extreme events of strong and weak EDW formation of this time period. We found that the Ekman transport is the indicator and driving mechanism explaining these extremes. Strong (Weak) EDW formation years correspond with atmospheric patterns resembling NAO− (NAO+), attributed to a strong (weak) winter air-sea surface heat loss, and a strong (weak) winter heat loss due to Ekman transport. Further, we show that such extreme Ekman advection patterns can be linked to mid-latitude storms, of which both intensity and duration have an impact on the extreme of EDW ventilation in the western subtropical North Atlantic. To yield a strong EDW formation, it requires a large winter heat deficit due to Ekman divergence, which can be sufficiently represented by numbers of strong winter storms, most notably, remnants of hurricanes and US east coast snowstorms. Meanwhile, to yield a weak EDW formation, apart from weak atmospheric forcings, a remnant positive heat content anomaly carried through from previous years would serve as an unfavorable preconditioning, hindering the EDW formation. Article in Journal/Newspaper North Atlantic Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Journal of Geophysical Research: Oceans 127 1 |
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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 Li, Ke Maze, Guillaume Mercier, Herlé Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water |
topic_facet |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
description |
International audience In the North Atlantic subtropical gyre, the Eighteen Degree Water (EDW) is a voluminous heat reservoir, submerged under a seasonal pycnocline that can be progressively removed through the winter, allowing EDW ventilation in the early spring. We target the EDW formation extremes, namely 2004–2005, 2009–2010, and 2012–2013 for the strong years, and 2007–2008, 2008–2009, 2011–2012, and 2013–2014 for the weak years. We employ gridded hydrographic datasets mainly measured by Argo floats over the last 20 years, and provide a synthetic study on the extreme events of strong and weak EDW formation of this time period. We found that the Ekman transport is the indicator and driving mechanism explaining these extremes. Strong (Weak) EDW formation years correspond with atmospheric patterns resembling NAO− (NAO+), attributed to a strong (weak) winter air-sea surface heat loss, and a strong (weak) winter heat loss due to Ekman transport. Further, we show that such extreme Ekman advection patterns can be linked to mid-latitude storms, of which both intensity and duration have an impact on the extreme of EDW ventilation in the western subtropical North Atlantic. To yield a strong EDW formation, it requires a large winter heat deficit due to Ekman divergence, which can be sufficiently represented by numbers of strong winter storms, most notably, remnants of hurricanes and US east coast snowstorms. Meanwhile, to yield a weak EDW formation, apart from weak atmospheric forcings, a remnant positive heat content anomaly carried through from previous years would serve as an unfavorable preconditioning, hindering the EDW formation. |
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 |
Li, Ke Maze, Guillaume Mercier, Herlé |
author_facet |
Li, Ke Maze, Guillaume Mercier, Herlé |
author_sort |
Li, Ke |
title |
Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water |
title_short |
Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water |
title_full |
Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water |
title_fullStr |
Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water |
title_full_unstemmed |
Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water |
title_sort |
ekman transport as the driver of extreme interannual formation rates of eighteen degree water |
publisher |
HAL CCSD |
publishDate |
2022 |
url |
https://hal.science/hal-03814771 https://hal.science/hal-03814771/document https://hal.science/hal-03814771/file/90674.pdf https://doi.org/10.1029/2021jc017696 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
ISSN: 2169-9275 EISSN: 2169-9291 Journal of Geophysical Research. Oceans https://hal.science/hal-03814771 Journal of Geophysical Research. Oceans, 2022, 127 (1), pp.e2021JC017696. ⟨10.1029/2021jc017696⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2021jc017696 hal-03814771 https://hal.science/hal-03814771 https://hal.science/hal-03814771/document https://hal.science/hal-03814771/file/90674.pdf doi:10.1029/2021jc017696 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1029/2021jc017696 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
127 |
container_issue |
1 |
_version_ |
1785569959768752128 |