Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals?
The temporal variability of the Atlantic Meridional Overturning Circulation (AMOC) is driven both by direct wind stresses and by the buoyancy-driven formation of North Atlantic Deep Water over the Labrador Sea and Nordic Seas. In many models, low-frequency density variability down the western bounda...
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2020
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ftdoajarticles:oai:doaj.org/article:f9e3c7c0b2a941a2ae18252c9057a648 2023-05-15T17:06:12+02:00 Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals? I. Polo K. Haines J. Robson C. Thomas 2020-09-01T00:00:00Z https://doi.org/10.5194/os-16-1067-2020 https://doaj.org/article/f9e3c7c0b2a941a2ae18252c9057a648 EN eng Copernicus Publications https://os.copernicus.org/articles/16/1067/2020/os-16-1067-2020.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 doi:10.5194/os-16-1067-2020 1812-0784 1812-0792 https://doaj.org/article/f9e3c7c0b2a941a2ae18252c9057a648 Ocean Science, Vol 16, Pp 1067-1088 (2020) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2020 ftdoajarticles https://doi.org/10.5194/os-16-1067-2020 2022-12-31T03:16:58Z The temporal variability of the Atlantic Meridional Overturning Circulation (AMOC) is driven both by direct wind stresses and by the buoyancy-driven formation of North Atlantic Deep Water over the Labrador Sea and Nordic Seas. In many models, low-frequency density variability down the western boundary of the Atlantic basin is linked to changes in the buoyancy forcing over the Atlantic subpolar gyre (SPG) region, and this is found to explain part of the geostrophic AMOC variability at 26 ∘ N. In this study, using different experiments with an ocean general circulation model (OGCM), we develop statistical methods to identify characteristic vertical density profiles at 26 ∘ N at the western and eastern boundaries, which relate to the buoyancy-forced AMOC. We show that density anomalies due to anomalous buoyancy forcing over the SPG propagate equatorward along the western Atlantic boundary (through 26 ∘ N), eastward along the Equator, and then poleward up the eastern Atlantic boundary. The timing of the density anomalies appearing at the western and eastern boundaries at 26 ∘ N reveals ∼ 2–3-year lags between boundaries along deeper levels (2600–3000 m). Record lengths of more than 26 years are required at the western boundary (WB) to allow the buoyancy-forced signals to appear as the dominant empirical orthogonal function (EOF) mode. Results suggest that the depth structure of the signals and the lagged covariances between the boundaries at 26 ∘ N may both provide useful information for detecting propagating signals of high-latitude origin in more complex models and potentially in the observational RAPID (Rapid Climate Change programme) array. However, time filtering may be needed, together with the continuation of the RAPID programme, in order to extend the time period. Article in Journal/Newspaper Labrador Sea Nordic Seas North Atlantic Deep Water North Atlantic Directory of Open Access Journals: DOAJ Articles Ocean Science 16 5 1067 1088 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
spellingShingle |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 I. Polo K. Haines J. Robson C. Thomas Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals? |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
The temporal variability of the Atlantic Meridional Overturning Circulation (AMOC) is driven both by direct wind stresses and by the buoyancy-driven formation of North Atlantic Deep Water over the Labrador Sea and Nordic Seas. In many models, low-frequency density variability down the western boundary of the Atlantic basin is linked to changes in the buoyancy forcing over the Atlantic subpolar gyre (SPG) region, and this is found to explain part of the geostrophic AMOC variability at 26 ∘ N. In this study, using different experiments with an ocean general circulation model (OGCM), we develop statistical methods to identify characteristic vertical density profiles at 26 ∘ N at the western and eastern boundaries, which relate to the buoyancy-forced AMOC. We show that density anomalies due to anomalous buoyancy forcing over the SPG propagate equatorward along the western Atlantic boundary (through 26 ∘ N), eastward along the Equator, and then poleward up the eastern Atlantic boundary. The timing of the density anomalies appearing at the western and eastern boundaries at 26 ∘ N reveals ∼ 2–3-year lags between boundaries along deeper levels (2600–3000 m). Record lengths of more than 26 years are required at the western boundary (WB) to allow the buoyancy-forced signals to appear as the dominant empirical orthogonal function (EOF) mode. Results suggest that the depth structure of the signals and the lagged covariances between the boundaries at 26 ∘ N may both provide useful information for detecting propagating signals of high-latitude origin in more complex models and potentially in the observational RAPID (Rapid Climate Change programme) array. However, time filtering may be needed, together with the continuation of the RAPID programme, in order to extend the time period. |
format |
Article in Journal/Newspaper |
author |
I. Polo K. Haines J. Robson C. Thomas |
author_facet |
I. Polo K. Haines J. Robson C. Thomas |
author_sort |
I. Polo |
title |
Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals? |
title_short |
Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals? |
title_full |
Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals? |
title_fullStr |
Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals? |
title_full_unstemmed |
Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals? |
title_sort |
can the boundary profiles at 26° n be used to extract buoyancy-forced atlantic meridional overturning circulation signals? |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/os-16-1067-2020 https://doaj.org/article/f9e3c7c0b2a941a2ae18252c9057a648 |
genre |
Labrador Sea Nordic Seas North Atlantic Deep Water North Atlantic |
genre_facet |
Labrador Sea Nordic Seas North Atlantic Deep Water North Atlantic |
op_source |
Ocean Science, Vol 16, Pp 1067-1088 (2020) |
op_relation |
https://os.copernicus.org/articles/16/1067/2020/os-16-1067-2020.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 doi:10.5194/os-16-1067-2020 1812-0784 1812-0792 https://doaj.org/article/f9e3c7c0b2a941a2ae18252c9057a648 |
op_doi |
https://doi.org/10.5194/os-16-1067-2020 |
container_title |
Ocean Science |
container_volume |
16 |
container_issue |
5 |
container_start_page |
1067 |
op_container_end_page |
1088 |
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1766061236958527488 |