On the mechanisms behind decadal heat content changes in the eastern subpolar gyre
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 si...
Published in: | Progress in Oceanography |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
2014
|
Subjects: | |
Online Access: | http://nora.nerc.ac.uk/id/eprint/513622/ https://doi.org/10.1016/j.pocean.2014.02.005 |
id |
ftnerc:oai:nora.nerc.ac.uk:513622 |
---|---|
record_format |
openpolar |
spelling |
ftnerc:oai:nora.nerc.ac.uk:513622 2023-05-15T15:51:50+02:00 On the mechanisms behind decadal heat content changes in the eastern subpolar gyre Desbruyeres, Damien Mercier, Herlé Thierry, Virginie 2014-03 http://nora.nerc.ac.uk/id/eprint/513622/ https://doi.org/10.1016/j.pocean.2014.02.005 unknown Desbruyeres, Damien; Mercier, Herlé; Thierry, Virginie. 2014 On the mechanisms behind decadal heat content changes in the eastern subpolar gyre. Progress in Oceanography, 132. 262-272. https://doi.org/10.1016/j.pocean.2014.02.005 <https://doi.org/10.1016/j.pocean.2014.02.005> Marine Sciences Publication - Article PeerReviewed 2014 ftnerc https://doi.org/10.1016/j.pocean.2014.02.005 2023-02-04T19:43:02Z 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 Natural Environment Research Council: NERC Open Research Archive Greenland Reykjanes ENVELOPE(-22.250,-22.250,65.467,65.467) Progress in Oceanography 132 262 272 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
topic |
Marine Sciences |
spellingShingle |
Marine Sciences Desbruyeres, Damien Mercier, Herlé Thierry, Virginie On the mechanisms behind decadal heat content changes in the eastern subpolar gyre |
topic_facet |
Marine Sciences |
description |
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. |
format |
Article in Journal/Newspaper |
author |
Desbruyeres, Damien Mercier, Herlé Thierry, Virginie |
author_facet |
Desbruyeres, Damien Mercier, Herlé Thierry, Virginie |
author_sort |
Desbruyeres, 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 |
publishDate |
2014 |
url |
http://nora.nerc.ac.uk/id/eprint/513622/ 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_relation |
Desbruyeres, Damien; Mercier, Herlé; Thierry, Virginie. 2014 On the mechanisms behind decadal heat content changes in the eastern subpolar gyre. Progress in Oceanography, 132. 262-272. https://doi.org/10.1016/j.pocean.2014.02.005 <https://doi.org/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_ |
1766387216626483200 |