Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation
It is typically assumed that the meridional density gradient in the North Atlantic is well and positively correlated with the Atlantic meridional overturning circulation (AMOC). In numerical “water-hosing” experiments, for example, imposing an anomalous freshwater flux in the Northern Hemisphere lea...
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ftsouthampton:oai:eprints.soton.ac.uk:392017 2023-08-27T04:10:53+02:00 Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation Sevellec, Florian Huck, Thierry 2016-03 text https://eprints.soton.ac.uk/392017/ https://eprints.soton.ac.uk/392017/1/jpo-d-14-0148%25252E1.pdf en English eng https://eprints.soton.ac.uk/392017/1/jpo-d-14-0148%25252E1.pdf Sevellec, Florian and Huck, Thierry (2016) Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation. Journal of Physical Oceanography, 46 (3), 895-917. (doi:10.1175/JPO-D-14-0148.1 <http://dx.doi.org/10.1175/JPO-D-14-0148.1>). cc_by_4 Article PeerReviewed 2016 ftsouthampton https://doi.org/10.1175/JPO-D-14-0148.1 2023-08-03T22:21:37Z It is typically assumed that the meridional density gradient in the North Atlantic is well and positively correlated with the Atlantic meridional overturning circulation (AMOC). In numerical “water-hosing” experiments, for example, imposing an anomalous freshwater flux in the Northern Hemisphere leads to a slowdown of the AMOC. However, on planetary scale, the first-order dynamics are linked to the geostrophic balance, relating the north–south pressure gradient to the zonal circulation. In this study, these two approaches are reconciled. At steady state and under geostrophic dynamics, an analytical expression is derived to relate the zonal and meridional pressure gradient. This solution is only valid where the meridional density gradient length scale is shorter than Earth’s curvature length scale, that is, north of 35°N. This theoretical expression links the north–south density gradient to the AMOC and can be used as a closure for zonally averaged ocean models. Assumptions and shortcomings of the approach are presented. Implications of these results for paleoclimate problems such as AMOC collapse and asymmetry in the meridional overturning circulation of the Atlantic and of the Pacific are discussed. Article in Journal/Newspaper North Atlantic University of Southampton: e-Prints Soton Pacific Journal of Physical Oceanography 46 3 895 917 |
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University of Southampton: e-Prints Soton |
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ftsouthampton |
language |
English |
description |
It is typically assumed that the meridional density gradient in the North Atlantic is well and positively correlated with the Atlantic meridional overturning circulation (AMOC). In numerical “water-hosing” experiments, for example, imposing an anomalous freshwater flux in the Northern Hemisphere leads to a slowdown of the AMOC. However, on planetary scale, the first-order dynamics are linked to the geostrophic balance, relating the north–south pressure gradient to the zonal circulation. In this study, these two approaches are reconciled. At steady state and under geostrophic dynamics, an analytical expression is derived to relate the zonal and meridional pressure gradient. This solution is only valid where the meridional density gradient length scale is shorter than Earth’s curvature length scale, that is, north of 35°N. This theoretical expression links the north–south density gradient to the AMOC and can be used as a closure for zonally averaged ocean models. Assumptions and shortcomings of the approach are presented. Implications of these results for paleoclimate problems such as AMOC collapse and asymmetry in the meridional overturning circulation of the Atlantic and of the Pacific are discussed. |
format |
Article in Journal/Newspaper |
author |
Sevellec, Florian Huck, Thierry |
spellingShingle |
Sevellec, Florian Huck, Thierry Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation |
author_facet |
Sevellec, Florian Huck, Thierry |
author_sort |
Sevellec, Florian |
title |
Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation |
title_short |
Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation |
title_full |
Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation |
title_fullStr |
Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation |
title_full_unstemmed |
Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation |
title_sort |
geostrophic closure of the zonally averaged atlantic meridional overturning circulation |
publishDate |
2016 |
url |
https://eprints.soton.ac.uk/392017/ https://eprints.soton.ac.uk/392017/1/jpo-d-14-0148%25252E1.pdf |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://eprints.soton.ac.uk/392017/1/jpo-d-14-0148%25252E1.pdf Sevellec, Florian and Huck, Thierry (2016) Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation. Journal of Physical Oceanography, 46 (3), 895-917. (doi:10.1175/JPO-D-14-0148.1 <http://dx.doi.org/10.1175/JPO-D-14-0148.1>). |
op_rights |
cc_by_4 |
op_doi |
https://doi.org/10.1175/JPO-D-14-0148.1 |
container_title |
Journal of Physical Oceanography |
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46 |
container_issue |
3 |
container_start_page |
895 |
op_container_end_page |
917 |
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1775353261368279040 |