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...
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ftinsu:oai:HAL:insu-03683306v1 2023-05-15T17:29:42+02:00 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-insu.archives-ouvertes.fr/insu-03683306 https://doi.org/10.1029/2021JC017696 en eng HAL CCSD info:eu-repo/semantics/altIdentifier/doi/10.1029/2021JC017696 insu-03683306 https://hal-insu.archives-ouvertes.fr/insu-03683306 BIBCODE: 2022JGRC.12717696L doi:10.1029/2021JC017696 Journal of Geophysical Research: Oceans https://hal-insu.archives-ouvertes.fr/insu-03683306 Journal of Geophysical Research: Oceans, 2022, 127, ⟨10.1029/2021JC017696⟩ North Atlantic Subtropical mode water Ekman current Argo floats subtropical gyre ocean stratification [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2022 ftinsu https://doi.org/10.1029/2021JC017696 2023-03-15T18:23:06Z 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 Institut national des sciences de l'Univers: HAL-INSU Journal of Geophysical Research: Oceans 127 1 |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
English |
topic |
North Atlantic Subtropical mode water Ekman current Argo floats subtropical gyre ocean stratification [SDU]Sciences of the Universe [physics] |
spellingShingle |
North Atlantic Subtropical mode water Ekman current Argo floats subtropical gyre ocean stratification [SDU]Sciences of the Universe [physics] Li, Ke Maze, Guillaume Mercier, Herlé Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water |
topic_facet |
North Atlantic Subtropical mode water Ekman current Argo floats subtropical gyre ocean stratification [SDU]Sciences of the Universe [physics] |
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-insu.archives-ouvertes.fr/insu-03683306 https://doi.org/10.1029/2021JC017696 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Journal of Geophysical Research: Oceans https://hal-insu.archives-ouvertes.fr/insu-03683306 Journal of Geophysical Research: Oceans, 2022, 127, ⟨10.1029/2021JC017696⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2021JC017696 insu-03683306 https://hal-insu.archives-ouvertes.fr/insu-03683306 BIBCODE: 2022JGRC.12717696L doi:10.1029/2021JC017696 |
op_doi |
https://doi.org/10.1029/2021JC017696 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
127 |
container_issue |
1 |
_version_ |
1766124490609131520 |