Meridional Overturning Transports at 7.5 N and 24.5 N in the Atlantic Ocean during 1992-93 and 2010-11
Transatlantic hydrographic sections along latitudes 7.5N and 24.5N have been repeated with about 20 years difference, at the beginning of the 1990s and 2010s. For each period, an inverse model is applied to the closed box bound by both sections. The model imposes mass conservation for individual lay...
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2014
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Online Access: | http://hdl.handle.net/10508/2641 http://hdl.handle.net/10261/318223 https://doi.org/10.1016/j.pocean.2014.08.016 |
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ftcsic:oai:digital.csic.es:10261/318223 2024-02-11T09:56:37+01:00 Meridional Overturning Transports at 7.5 N and 24.5 N in the Atlantic Ocean during 1992-93 and 2010-11 Hernández-Guerra, Alonso Pelegrí-Llopart, José Luis Fraile-Nuez, Eugenio Benítez-Barrios, Verónica María Emelianov, Mikhail Pérez-Hernández, María Dolores Vélez-Belchí, Pedro Atlantic Ocean Central Atlantic Tropical Atlantic 2014-09 http://hdl.handle.net/10508/2641 http://hdl.handle.net/10261/318223 https://doi.org/10.1016/j.pocean.2014.08.016 en eng Centro Oceanográfico de Canarias AM Progress in Oceanography, 1. 2014: 1-17 0079-6611 http://hdl.handle.net/10508/2641 http://hdl.handle.net/10261/318223 doi:10.1016/j.pocean.2014.08.016 20393 open Medio Marino Centro Oceanográfico de Canarias research article 2014 ftcsic https://doi.org/10.1016/j.pocean.2014.08.016 2024-01-16T11:45:03Z Transatlantic hydrographic sections along latitudes 7.5N and 24.5N have been repeated with about 20 years difference, at the beginning of the 1990s and 2010s. For each period, an inverse model is applied to the closed box bound by both sections. The model imposes mass conservation for individual layers, defined by isoneutral surfaces, and the whole water column, using surface Ekman transport and several transport constraints for specific ranges of longitudes and depths. As a result, the velocities at the reference layer for each station pair and the dianeutral velocities between layers are estimated, and the horizontal velocity fields and the water, heat and freshwater transports are calculated; in particular, we find that mass transport per stratum at 24.5N in 2011 is in good agreement with the transport estimates from the RAPID-Watch array. During both realizations the dianeutral velocities downwell from the Upper North Atlantic Deep Water (UNADW) to the Lower North Atlantic Deep Water (LNADW) strata, resulting in the merging of the two southward flowing strata at 24.5N into one deep southward-moving stratum at 7.5N. At 24.5N, there is an increase in southward UNADW transport between 1992 and 2011, compensated by a decrease of southward LNADW transport; a descent in the upper limit of the Antarctic Bottom Water (AABW) from 1992 to 2011 is also inferred. The Atlantic Meridional Overturning Circulation (AMOC) is larger in 1992–93 than in 2010–11, decreasing from 24.7 ± 1.7 to 20.1 ± 1.4 Sv at 24.5N and from 29.2 ± 1.7 to 16.9 ± 1.5 Sv at 7.5N. Much of this decrease arises because of the northward flow of Antarctic Intermediate Water (AAIW), which was much more intense in 1992–93 than in 2010–11. As a consequence, heat transport at 24.5N is not significantly different in 1992 (1.4 ± 0.1 PW) and 2011 (1.2 ± 0.1 PW). The estimation of heat transport at 7.5N strongly depends on the magnitude of the North Brazil Current over the American continental platform. The freshwater flux into the box bounded by the two ... Article in Journal/Newspaper Antarc* Antarctic North Atlantic Deep Water North Atlantic Digital.CSIC (Spanish National Research Council) Antarctic The Antarctic Progress in Oceanography 128 98 114 |
institution |
Open Polar |
collection |
Digital.CSIC (Spanish National Research Council) |
op_collection_id |
ftcsic |
language |
English |
topic |
Medio Marino Centro Oceanográfico de Canarias |
spellingShingle |
Medio Marino Centro Oceanográfico de Canarias Hernández-Guerra, Alonso Pelegrí-Llopart, José Luis Fraile-Nuez, Eugenio Benítez-Barrios, Verónica María Emelianov, Mikhail Pérez-Hernández, María Dolores Vélez-Belchí, Pedro Meridional Overturning Transports at 7.5 N and 24.5 N in the Atlantic Ocean during 1992-93 and 2010-11 |
topic_facet |
Medio Marino Centro Oceanográfico de Canarias |
description |
Transatlantic hydrographic sections along latitudes 7.5N and 24.5N have been repeated with about 20 years difference, at the beginning of the 1990s and 2010s. For each period, an inverse model is applied to the closed box bound by both sections. The model imposes mass conservation for individual layers, defined by isoneutral surfaces, and the whole water column, using surface Ekman transport and several transport constraints for specific ranges of longitudes and depths. As a result, the velocities at the reference layer for each station pair and the dianeutral velocities between layers are estimated, and the horizontal velocity fields and the water, heat and freshwater transports are calculated; in particular, we find that mass transport per stratum at 24.5N in 2011 is in good agreement with the transport estimates from the RAPID-Watch array. During both realizations the dianeutral velocities downwell from the Upper North Atlantic Deep Water (UNADW) to the Lower North Atlantic Deep Water (LNADW) strata, resulting in the merging of the two southward flowing strata at 24.5N into one deep southward-moving stratum at 7.5N. At 24.5N, there is an increase in southward UNADW transport between 1992 and 2011, compensated by a decrease of southward LNADW transport; a descent in the upper limit of the Antarctic Bottom Water (AABW) from 1992 to 2011 is also inferred. The Atlantic Meridional Overturning Circulation (AMOC) is larger in 1992–93 than in 2010–11, decreasing from 24.7 ± 1.7 to 20.1 ± 1.4 Sv at 24.5N and from 29.2 ± 1.7 to 16.9 ± 1.5 Sv at 7.5N. Much of this decrease arises because of the northward flow of Antarctic Intermediate Water (AAIW), which was much more intense in 1992–93 than in 2010–11. As a consequence, heat transport at 24.5N is not significantly different in 1992 (1.4 ± 0.1 PW) and 2011 (1.2 ± 0.1 PW). The estimation of heat transport at 7.5N strongly depends on the magnitude of the North Brazil Current over the American continental platform. The freshwater flux into the box bounded by the two ... |
format |
Article in Journal/Newspaper |
author |
Hernández-Guerra, Alonso Pelegrí-Llopart, José Luis Fraile-Nuez, Eugenio Benítez-Barrios, Verónica María Emelianov, Mikhail Pérez-Hernández, María Dolores Vélez-Belchí, Pedro |
author_facet |
Hernández-Guerra, Alonso Pelegrí-Llopart, José Luis Fraile-Nuez, Eugenio Benítez-Barrios, Verónica María Emelianov, Mikhail Pérez-Hernández, María Dolores Vélez-Belchí, Pedro |
author_sort |
Hernández-Guerra, Alonso |
title |
Meridional Overturning Transports at 7.5 N and 24.5 N in the Atlantic Ocean during 1992-93 and 2010-11 |
title_short |
Meridional Overturning Transports at 7.5 N and 24.5 N in the Atlantic Ocean during 1992-93 and 2010-11 |
title_full |
Meridional Overturning Transports at 7.5 N and 24.5 N in the Atlantic Ocean during 1992-93 and 2010-11 |
title_fullStr |
Meridional Overturning Transports at 7.5 N and 24.5 N in the Atlantic Ocean during 1992-93 and 2010-11 |
title_full_unstemmed |
Meridional Overturning Transports at 7.5 N and 24.5 N in the Atlantic Ocean during 1992-93 and 2010-11 |
title_sort |
meridional overturning transports at 7.5 n and 24.5 n in the atlantic ocean during 1992-93 and 2010-11 |
publishDate |
2014 |
url |
http://hdl.handle.net/10508/2641 http://hdl.handle.net/10261/318223 https://doi.org/10.1016/j.pocean.2014.08.016 |
op_coverage |
Atlantic Ocean Central Atlantic Tropical Atlantic |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic North Atlantic Deep Water North Atlantic |
genre_facet |
Antarc* Antarctic North Atlantic Deep Water North Atlantic |
op_relation |
Centro Oceanográfico de Canarias AM Progress in Oceanography, 1. 2014: 1-17 0079-6611 http://hdl.handle.net/10508/2641 http://hdl.handle.net/10261/318223 doi:10.1016/j.pocean.2014.08.016 20393 |
op_rights |
open |
op_doi |
https://doi.org/10.1016/j.pocean.2014.08.016 |
container_title |
Progress in Oceanography |
container_volume |
128 |
container_start_page |
98 |
op_container_end_page |
114 |
_version_ |
1790604527739600896 |