Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals?
<p>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 weste...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-09-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/16/1067/2020/os-16-1067-2020.pdf |
| _version_ | 1818258652686974976 |
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| author | I. Polo I. Polo K. Haines J. Robson C. Thomas |
| author_facet | I. Polo I. Polo K. Haines J. Robson C. Thomas |
| author_sort | I. Polo |
| collection | DOAJ |
| description | <p>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<span class="inline-formula"><sup>∘</sup></span> 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<span class="inline-formula"><sup>∘</sup></span> 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<span class="inline-formula"><sup>∘</sup></span> 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<span class="inline-formula"><sup>∘</sup></span> N reveals <span class="inline-formula">∼</span> 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<span class="inline-formula"><sup>∘</sup></span> 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.</p> |
| first_indexed | 2024-12-12T18:02:57Z |
| format | Article |
| id | doaj.art-f9e3c7c0b2a941a2ae18252c9057a648 |
| institution | Directory Open Access Journal |
| issn | 1812-0784 1812-0792 |
| language | English |
| last_indexed | 2024-12-12T18:02:57Z |
| publishDate | 2020-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Ocean Science |
| spelling | doaj.art-f9e3c7c0b2a941a2ae18252c9057a6482022-12-22T00:16:35ZengCopernicus PublicationsOcean Science1812-07841812-07922020-09-01161067108810.5194/os-16-1067-2020Can the boundary profiles at 26° N be used to extract buoyancy-forced Atlantic Meridional Overturning Circulation signals?I. Polo0I. Polo1K. Haines2J. Robson3C. Thomas4Department of Meteorology, University of Reading, Reading, RG6 6BB, United KingdomDepartamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, Madrid, 28040, SpainDepartment of Meteorology, University of Reading, Reading, RG6 6BB, United KingdomDepartment of Meteorology, University of Reading, Reading, RG6 6BB, United KingdomDepartment of Meteorology, University of Reading, Reading, RG6 6BB, United Kingdom<p>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<span class="inline-formula"><sup>∘</sup></span> 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<span class="inline-formula"><sup>∘</sup></span> 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<span class="inline-formula"><sup>∘</sup></span> 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<span class="inline-formula"><sup>∘</sup></span> N reveals <span class="inline-formula">∼</span> 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<span class="inline-formula"><sup>∘</sup></span> 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.</p>https://os.copernicus.org/articles/16/1067/2020/os-16-1067-2020.pdf |
| spellingShingle | I. Polo 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? Ocean Science |
| title | 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_short | 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° thinsp n be used to extract buoyancy forced atlantic meridional overturning circulation signals |
| url | https://os.copernicus.org/articles/16/1067/2020/os-16-1067-2020.pdf |
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