Meridional overturning circulation: stability and ocean feedbacks in a box model
A box model of the inter-hemispheric Atlantic meridional overturning circulation is developed, including a variable pycnocline depth for the tropical and subtropical regions. The circulation is forced by winds over a periodic channel in the south and by freshwater forcing at the surface. The model i...
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ftunivutrecht:oai:dspace.library.uu.nl:1874/276156 2023-07-23T04:14:19+02:00 Meridional overturning circulation: stability and ocean feedbacks in a box model Cimatoribus, A.A. Drijfhout, S.S. Dijkstra, H.A. Marine and Atmospheric Research Sub Physical Oceanography 2014 application/pdf https://dspace.library.uu.nl/handle/1874/276156 en eng 0930-7575 https://dspace.library.uu.nl/handle/1874/276156 info:eu-repo/semantics/EmbargoedAccess Article 2014 ftunivutrecht 2023-07-02T00:41:49Z A box model of the inter-hemispheric Atlantic meridional overturning circulation is developed, including a variable pycnocline depth for the tropical and subtropical regions. The circulation is forced by winds over a periodic channel in the south and by freshwater forcing at the surface. The model is aimed at investigating the ocean feedbacks related to perturbations in freshwater forcing from the atmosphere, and to changes in freshwater transport in the ocean. These feedbacks are closely connected with the stability properties of the meridional overturning circulation, in particular in response to freshwater perturbations. A separate box is used for representing the region north of the Antarctic circumpolar current in the Atlantic sector. The density difference between this region and the north of the basin is then used for scaling the downwelling in the north. These choices are essential for reproducing the sensitivity of the meridional overturning circulation observed in general circulation models, and therefore suggest that the southernmost part of the Atlantic Ocean north of the Drake Passage is of fundamental importance for the stability of the meridional overturning circulation. With this configuration, the magnitude of the freshwater transport by the southern subtropical gyre strongly affects the response of the meridional overturning circulation to external forcing. The role of the freshwater transport by the overturning circulation (Mov) as a stability indicator is discussed. It is investigated under which conditions its sign at the latitude of the southern tip of Africa can provide information on the existence of a second, permanently shut down, state of the overturning circulation in the box model. Mov will be an adequate indicator of the existence of multiple equilibria only if salt-advection feedback dominates over other processes in determining the response of the circulation to freshwater anomalies. Mov is a perfect indicator if feedbacks other than salt-advection are negligible. Article in Journal/Newspaper Antarc* Antarctic Drake Passage Utrecht University Repository Antarctic Drake Passage The Antarctic |
institution |
Open Polar |
collection |
Utrecht University Repository |
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ftunivutrecht |
language |
English |
description |
A box model of the inter-hemispheric Atlantic meridional overturning circulation is developed, including a variable pycnocline depth for the tropical and subtropical regions. The circulation is forced by winds over a periodic channel in the south and by freshwater forcing at the surface. The model is aimed at investigating the ocean feedbacks related to perturbations in freshwater forcing from the atmosphere, and to changes in freshwater transport in the ocean. These feedbacks are closely connected with the stability properties of the meridional overturning circulation, in particular in response to freshwater perturbations. A separate box is used for representing the region north of the Antarctic circumpolar current in the Atlantic sector. The density difference between this region and the north of the basin is then used for scaling the downwelling in the north. These choices are essential for reproducing the sensitivity of the meridional overturning circulation observed in general circulation models, and therefore suggest that the southernmost part of the Atlantic Ocean north of the Drake Passage is of fundamental importance for the stability of the meridional overturning circulation. With this configuration, the magnitude of the freshwater transport by the southern subtropical gyre strongly affects the response of the meridional overturning circulation to external forcing. The role of the freshwater transport by the overturning circulation (Mov) as a stability indicator is discussed. It is investigated under which conditions its sign at the latitude of the southern tip of Africa can provide information on the existence of a second, permanently shut down, state of the overturning circulation in the box model. Mov will be an adequate indicator of the existence of multiple equilibria only if salt-advection feedback dominates over other processes in determining the response of the circulation to freshwater anomalies. Mov is a perfect indicator if feedbacks other than salt-advection are negligible. |
author2 |
Marine and Atmospheric Research Sub Physical Oceanography |
format |
Article in Journal/Newspaper |
author |
Cimatoribus, A.A. Drijfhout, S.S. Dijkstra, H.A. |
spellingShingle |
Cimatoribus, A.A. Drijfhout, S.S. Dijkstra, H.A. Meridional overturning circulation: stability and ocean feedbacks in a box model |
author_facet |
Cimatoribus, A.A. Drijfhout, S.S. Dijkstra, H.A. |
author_sort |
Cimatoribus, A.A. |
title |
Meridional overturning circulation: stability and ocean feedbacks in a box model |
title_short |
Meridional overturning circulation: stability and ocean feedbacks in a box model |
title_full |
Meridional overturning circulation: stability and ocean feedbacks in a box model |
title_fullStr |
Meridional overturning circulation: stability and ocean feedbacks in a box model |
title_full_unstemmed |
Meridional overturning circulation: stability and ocean feedbacks in a box model |
title_sort |
meridional overturning circulation: stability and ocean feedbacks in a box model |
publishDate |
2014 |
url |
https://dspace.library.uu.nl/handle/1874/276156 |
geographic |
Antarctic Drake Passage The Antarctic |
geographic_facet |
Antarctic Drake Passage The Antarctic |
genre |
Antarc* Antarctic Drake Passage |
genre_facet |
Antarc* Antarctic Drake Passage |
op_relation |
0930-7575 https://dspace.library.uu.nl/handle/1874/276156 |
op_rights |
info:eu-repo/semantics/EmbargoedAccess |
_version_ |
1772184068563140608 |