The University of Southampton
University of Southampton Institutional Repository

Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation

Geostrophic closure of the zonally averaged Atlantic meridional overturning circulation
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 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.
Geographic location/entity, Atlantic Ocean, Circulation/ Dynamics, Baroclinic flows, Meridional overturning circulation, Ocean circulation, Atm/Ocean Structure/ Phenomena, Ekman pumping, Thermohaline circulation
0022-3670
895-917
Sevellec, Florian
01569d6c-65b0-4270-af2a-35b0a77c9140
Huck, Thierry
3de8511b-db7b-4ed1-bc27-92d2bbc7c6b9
Sevellec, Florian
01569d6c-65b0-4270-af2a-35b0a77c9140
Huck, Thierry
3de8511b-db7b-4ed1-bc27-92d2bbc7c6b9

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).

Record type: Article

Abstract

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.

Text
jpo-d-14-0148%2E1.pdf - Version of Record
Available under License Creative Commons Attribution.
Download (3MB)

More information

Accepted/In Press date: 29 May 2015
Published date: March 2016
Keywords: Geographic location/entity, Atlantic Ocean, Circulation/ Dynamics, Baroclinic flows, Meridional overturning circulation, Ocean circulation, Atm/Ocean Structure/ Phenomena, Ekman pumping, Thermohaline circulation
Organisations: Physical Oceanography

Identifiers

Local EPrints ID: 392017
URI: http://eprints.soton.ac.uk/id/eprint/392017
ISSN: 0022-3670
PURE UUID: 7e99ba08-7983-4bc4-9493-9e87b139bd8c

Catalogue record

Date deposited: 12 Apr 2016 15:45
Last modified: 14 Mar 2024 23:33

Export record

Altmetrics

Contributors

Author: Thierry Huck

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×