On the mechanisms behind decadal heat content changes in the eastern subpolar gyre
International audience Historical and modern hydrographic data show substantial decadal variability in the heat content (HC) of the eastern subpolar North Atlantic. Those changes are here investigated in an eddy-permitting simulation (ORCA025-G70) forced by reanalysis products for the period 1965–20...
Published in: | Progress in Oceanography |
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Online Access: | https://hal.archives-ouvertes.fr/hal-01151399 https://doi.org/10.1016/j.pocean.2014.02.005 |
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ftccsdartic:oai:HAL:hal-01151399v1 2023-05-15T15:51:50+02:00 On the mechanisms behind decadal heat content changes in the eastern subpolar gyre Desbruyères, Damien Mercier, Herlé Thierry, Virginie Laboratoire de physique des océans (LPO) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS) 2015-03 https://hal.archives-ouvertes.fr/hal-01151399 https://doi.org/10.1016/j.pocean.2014.02.005 en eng HAL CCSD Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.pocean.2014.02.005 hal-01151399 https://hal.archives-ouvertes.fr/hal-01151399 doi:10.1016/j.pocean.2014.02.005 ISSN: 0079-6611 Progress in Oceanography https://hal.archives-ouvertes.fr/hal-01151399 Progress in Oceanography, Elsevier, 2015, 132, pp.262-272. ⟨10.1016/j.pocean.2014.02.005⟩ [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography info:eu-repo/semantics/article Journal articles 2015 ftccsdartic https://doi.org/10.1016/j.pocean.2014.02.005 2021-10-17T01:25:40Z International audience Historical and modern hydrographic data show substantial decadal variability in the heat content (HC) of the eastern subpolar North Atlantic. Those changes are here investigated in an eddy-permitting simulation (ORCA025-G70) forced by reanalysis products for the period 1965–2004. The observed and simulated decadal signal is characterized by a strong cooling in the 1960s and 1970s, a period of minor changes in the 1980s, and a strong warming in the 1990s and 2000s. A heat budget calculation is performed within a box bounded by the Greenland–Scotland sills and the Cape Farewell (Greenland)–Portugal A25-Ovide section. The decadal variability of HC is mainly governed by the integrated effect of anomalous oceanic heat transport across A25-Ovide (HTA25HTA25), with local air-sea heat fluxes playing a damping role. The impact of temperature changes acting upon the mean oceanic circulation is shown to dominate the long-term behavior of HTA25HTA25. Through Lagrangian experiments, we show that temperature anomalies advected by the mean circulation across A25-Ovide are mostly created by the gyre circulation anomalies upstream of A25-Ovide and the associated changes in the relative proportion of cold subpolar and warm subtropical waters feeding the northern and southern branches of the North Atlantic Current. These temperature anomalies induce large-scale changes in the pycnocline slope east of Reykjanes Ridge along A25-Ovide: when the NAC is relatively cold (warm), the main pycnocline moves upward (downward) in the Iceland Basin and on top of Reykjanes Ridge, thereby increasing (decreasing) the pycnocline slope. The resulting velocity anomalies lead to heat transport changes that strongly oppose the thermally-driven heat transport anomalies. Article in Journal/Newspaper Cape Farewell Greenland Iceland north atlantic current North Atlantic Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Greenland Reykjanes ENVELOPE(-22.250,-22.250,65.467,65.467) Progress in Oceanography 132 262 272 |
institution |
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 Desbruyères, Damien Mercier, Herlé Thierry, Virginie On the mechanisms behind decadal heat content changes in the eastern subpolar gyre |
topic_facet |
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
description |
International audience Historical and modern hydrographic data show substantial decadal variability in the heat content (HC) of the eastern subpolar North Atlantic. Those changes are here investigated in an eddy-permitting simulation (ORCA025-G70) forced by reanalysis products for the period 1965–2004. The observed and simulated decadal signal is characterized by a strong cooling in the 1960s and 1970s, a period of minor changes in the 1980s, and a strong warming in the 1990s and 2000s. A heat budget calculation is performed within a box bounded by the Greenland–Scotland sills and the Cape Farewell (Greenland)–Portugal A25-Ovide section. The decadal variability of HC is mainly governed by the integrated effect of anomalous oceanic heat transport across A25-Ovide (HTA25HTA25), with local air-sea heat fluxes playing a damping role. The impact of temperature changes acting upon the mean oceanic circulation is shown to dominate the long-term behavior of HTA25HTA25. Through Lagrangian experiments, we show that temperature anomalies advected by the mean circulation across A25-Ovide are mostly created by the gyre circulation anomalies upstream of A25-Ovide and the associated changes in the relative proportion of cold subpolar and warm subtropical waters feeding the northern and southern branches of the North Atlantic Current. These temperature anomalies induce large-scale changes in the pycnocline slope east of Reykjanes Ridge along A25-Ovide: when the NAC is relatively cold (warm), the main pycnocline moves upward (downward) in the Iceland Basin and on top of Reykjanes Ridge, thereby increasing (decreasing) the pycnocline slope. The resulting velocity anomalies lead to heat transport changes that strongly oppose the thermally-driven heat transport anomalies. |
author2 |
Laboratoire de physique des océans (LPO) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Desbruyères, Damien Mercier, Herlé Thierry, Virginie |
author_facet |
Desbruyères, Damien Mercier, Herlé Thierry, Virginie |
author_sort |
Desbruyères, Damien |
title |
On the mechanisms behind decadal heat content changes in the eastern subpolar gyre |
title_short |
On the mechanisms behind decadal heat content changes in the eastern subpolar gyre |
title_full |
On the mechanisms behind decadal heat content changes in the eastern subpolar gyre |
title_fullStr |
On the mechanisms behind decadal heat content changes in the eastern subpolar gyre |
title_full_unstemmed |
On the mechanisms behind decadal heat content changes in the eastern subpolar gyre |
title_sort |
on the mechanisms behind decadal heat content changes in the eastern subpolar gyre |
publisher |
HAL CCSD |
publishDate |
2015 |
url |
https://hal.archives-ouvertes.fr/hal-01151399 https://doi.org/10.1016/j.pocean.2014.02.005 |
long_lat |
ENVELOPE(-22.250,-22.250,65.467,65.467) |
geographic |
Greenland Reykjanes |
geographic_facet |
Greenland Reykjanes |
genre |
Cape Farewell Greenland Iceland north atlantic current North Atlantic |
genre_facet |
Cape Farewell Greenland Iceland north atlantic current North Atlantic |
op_source |
ISSN: 0079-6611 Progress in Oceanography https://hal.archives-ouvertes.fr/hal-01151399 Progress in Oceanography, Elsevier, 2015, 132, pp.262-272. ⟨10.1016/j.pocean.2014.02.005⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.pocean.2014.02.005 hal-01151399 https://hal.archives-ouvertes.fr/hal-01151399 doi:10.1016/j.pocean.2014.02.005 |
op_doi |
https://doi.org/10.1016/j.pocean.2014.02.005 |
container_title |
Progress in Oceanography |
container_volume |
132 |
container_start_page |
262 |
op_container_end_page |
272 |
_version_ |
1766387216259481600 |