Decadal variability of hydrography in the upper northern North Atlantic in 1948-1990
International audience We investigate the variability of the North Atlantic subarctic gyre in recent decades from time series of station temperature and salinity. Decadal variability stronger at the surface is identified, which exhibits vertical coherence over a layer deeper than the late winter mix...
Published in: | Journal of Geophysical Research: Oceans |
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Language: | English |
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ftinsu:oai:HAL:hal-00772202v1 2023-05-15T15:01:54+02:00 Decadal variability of hydrography in the upper northern North Atlantic in 1948-1990 Reverdin, Gilles Cayan, D. Kushnir, Y. Laboratoire d'océanographie dynamique et de climatologie (LODYC) Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS) 1997-04 https://hal.science/hal-00772202 https://hal.science/hal-00772202/document https://hal.science/hal-00772202/file/96JC03943.pdf https://doi.org/10.1029/96JC03943 en eng HAL CCSD American Geophysical Union info:eu-repo/semantics/altIdentifier/doi/10.1029/96JC03943 hal-00772202 https://hal.science/hal-00772202 https://hal.science/hal-00772202/document https://hal.science/hal-00772202/file/96JC03943.pdf BIBCODE: 1997JGR.102.8505R doi:10.1029/96JC03943 info:eu-repo/semantics/OpenAccess ISSN: 0148-0227 EISSN: 2156-2202 Journal of Geophysical Research https://hal.science/hal-00772202 Journal of Geophysical Research, 1997, 102, pp.8505-8532. ⟨10.1029/96JC03943⟩ Oceanography: Physical: Sea level variations Oceanography: General: Climate and interannual variability Oceanography: Physical: Hydrography Oceanography: Physical: Upper ocean processes [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] info:eu-repo/semantics/article Journal articles 1997 ftinsu https://doi.org/10.1029/96JC03943 2023-01-18T17:25:27Z International audience We investigate the variability of the North Atlantic subarctic gyre in recent decades from time series of station temperature and salinity. Decadal variability stronger at the surface is identified, which exhibits vertical coherence over a layer deeper than the late winter mixed layer. In the northwestern Atlantic, it corresponds to the layer with a component of water from the Arctic Ocean or from the Canadian Arctic. The spatial coherence of the signal is investigated. An empirical orthogonal function decomposition of lagged time series indicates that a single pattern explains 70% of the variance in upper ocean salt content, corresponding to a propagating signal from the west to the northeast in the subarctic gyre. The most likely interpretation is that the salinity signal originates in the slope currents of the Labrador Sea and is diffused/advected eastward of the Grand Banks over the near western Atlantic. In the northwestern Atlantic, temperature fluctuations are strongly correlated to salinity fluctuations and are aligned along the average T-S characteristics. This signal suggests large variations in the outflow of fresh, cold water in the slope current, and is strongly correlated with ice cover. A basin scale atmospheric circulation of weakened westerlies at 55°N, weaker northwesterlies west of Greenland and weaker southerlies over the central and eastern North Atlantic is associated with the high salinity and warm water phase of the first principal component. This circulation pattern leads fluctuations in the northeast Atlantic and lags those in the northwestern part of the basin. The wind indices also suggest that the fluctuations of the fresh water outflow occur during intervals of anomalously northerly winds, either east of Greenland (1965, 1968-1969) or off the Canadian Archipelago (1983-1984). Article in Journal/Newspaper Arctic Arctic Ocean Canadian Archipelago Greenland Labrador Sea North Atlantic Northeast Atlantic Subarctic Institut national des sciences de l'Univers: HAL-INSU Arctic Arctic Ocean Greenland Journal of Geophysical Research: Oceans 102 C4 8505 8531 |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
English |
topic |
Oceanography: Physical: Sea level variations Oceanography: General: Climate and interannual variability Oceanography: Physical: Hydrography Oceanography: Physical: Upper ocean processes [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] |
spellingShingle |
Oceanography: Physical: Sea level variations Oceanography: General: Climate and interannual variability Oceanography: Physical: Hydrography Oceanography: Physical: Upper ocean processes [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] Reverdin, Gilles Cayan, D. Kushnir, Y. Decadal variability of hydrography in the upper northern North Atlantic in 1948-1990 |
topic_facet |
Oceanography: Physical: Sea level variations Oceanography: General: Climate and interannual variability Oceanography: Physical: Hydrography Oceanography: Physical: Upper ocean processes [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] |
description |
International audience We investigate the variability of the North Atlantic subarctic gyre in recent decades from time series of station temperature and salinity. Decadal variability stronger at the surface is identified, which exhibits vertical coherence over a layer deeper than the late winter mixed layer. In the northwestern Atlantic, it corresponds to the layer with a component of water from the Arctic Ocean or from the Canadian Arctic. The spatial coherence of the signal is investigated. An empirical orthogonal function decomposition of lagged time series indicates that a single pattern explains 70% of the variance in upper ocean salt content, corresponding to a propagating signal from the west to the northeast in the subarctic gyre. The most likely interpretation is that the salinity signal originates in the slope currents of the Labrador Sea and is diffused/advected eastward of the Grand Banks over the near western Atlantic. In the northwestern Atlantic, temperature fluctuations are strongly correlated to salinity fluctuations and are aligned along the average T-S characteristics. This signal suggests large variations in the outflow of fresh, cold water in the slope current, and is strongly correlated with ice cover. A basin scale atmospheric circulation of weakened westerlies at 55°N, weaker northwesterlies west of Greenland and weaker southerlies over the central and eastern North Atlantic is associated with the high salinity and warm water phase of the first principal component. This circulation pattern leads fluctuations in the northeast Atlantic and lags those in the northwestern part of the basin. The wind indices also suggest that the fluctuations of the fresh water outflow occur during intervals of anomalously northerly winds, either east of Greenland (1965, 1968-1969) or off the Canadian Archipelago (1983-1984). |
author2 |
Laboratoire d'océanographie dynamique et de climatologie (LODYC) Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Reverdin, Gilles Cayan, D. Kushnir, Y. |
author_facet |
Reverdin, Gilles Cayan, D. Kushnir, Y. |
author_sort |
Reverdin, Gilles |
title |
Decadal variability of hydrography in the upper northern North Atlantic in 1948-1990 |
title_short |
Decadal variability of hydrography in the upper northern North Atlantic in 1948-1990 |
title_full |
Decadal variability of hydrography in the upper northern North Atlantic in 1948-1990 |
title_fullStr |
Decadal variability of hydrography in the upper northern North Atlantic in 1948-1990 |
title_full_unstemmed |
Decadal variability of hydrography in the upper northern North Atlantic in 1948-1990 |
title_sort |
decadal variability of hydrography in the upper northern north atlantic in 1948-1990 |
publisher |
HAL CCSD |
publishDate |
1997 |
url |
https://hal.science/hal-00772202 https://hal.science/hal-00772202/document https://hal.science/hal-00772202/file/96JC03943.pdf https://doi.org/10.1029/96JC03943 |
geographic |
Arctic Arctic Ocean Greenland |
geographic_facet |
Arctic Arctic Ocean Greenland |
genre |
Arctic Arctic Ocean Canadian Archipelago Greenland Labrador Sea North Atlantic Northeast Atlantic Subarctic |
genre_facet |
Arctic Arctic Ocean Canadian Archipelago Greenland Labrador Sea North Atlantic Northeast Atlantic Subarctic |
op_source |
ISSN: 0148-0227 EISSN: 2156-2202 Journal of Geophysical Research https://hal.science/hal-00772202 Journal of Geophysical Research, 1997, 102, pp.8505-8532. ⟨10.1029/96JC03943⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/96JC03943 hal-00772202 https://hal.science/hal-00772202 https://hal.science/hal-00772202/document https://hal.science/hal-00772202/file/96JC03943.pdf BIBCODE: 1997JGR.102.8505R doi:10.1029/96JC03943 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1029/96JC03943 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
102 |
container_issue |
C4 |
container_start_page |
8505 |
op_container_end_page |
8531 |
_version_ |
1766333904534372352 |