Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation
Freshwater hosing experiments with a comprehensive coupled climate model and a coupled model of intermediate complexity are performed with and without global salt compensation in order to investigate the robustness of the bipolar seesaw. In both cases, a strong reduction of the Atlantic meridional o...
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ftunivbern:oai:boris.unibe.ch:25267 2023-08-20T04:09:55+02:00 Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation Stocker, Thomas F. Timmermann, Axel Renold, Manuel Timm, Oliver 2007 application/pdf https://boris.unibe.ch/25267/1/2007jcli1662%252E1.pdf https://boris.unibe.ch/25267/ eng eng American Meteorological Society https://boris.unibe.ch/25267/ info:eu-repo/semantics/openAccess Stocker, Thomas F.; Timmermann, Axel; Renold, Manuel; Timm, Oliver (2007). Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation. Journal of Climate, 20(24), pp. 5912-5928. American Meteorological Society 10.1175/2007JCLI1662.1 <http://dx.doi.org/10.1175/2007JCLI1662.1> 530 Physics info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion PeerReviewed 2007 ftunivbern https://doi.org/10.1175/2007JCLI1662.1 2023-07-31T20:48:45Z Freshwater hosing experiments with a comprehensive coupled climate model and a coupled model of intermediate complexity are performed with and without global salt compensation in order to investigate the robustness of the bipolar seesaw. In both cases, a strong reduction of the Atlantic meridional overturning circulation is induced, and a warming in the South Atlantic results. When a globally uniform salt flux is applied at the surface in order to keep the global mean salinity constant, this causes additional widespread warming in the Southern Ocean. It is shown that this warming is mainly due to heat transport anomalies that are induced by the specific parameterization in ocean models to represent eddy mixing. Surface salt fluxes tend to move outcropping isopycnals equatorward. As the density perturbation originates at the surface, changes in isopycnal slopes are generated that lead to anomalies in the bolus velocity field. The associated bolus heat flux convergence creates a warming enhancing the bipolar seesaw response, particularly in the Southern Ocean. The importance of this mechanism is illustrated in coupled model simulations in which this parameterization in the ocean model component is switched on or off. Additional experiments in which the same total amount of freshwater is delivered at rates 10 times smaller show that the effect of the global salt compensation is not important in this case, but that the eddy-mixing parameterization is still responsible for a substantial temperature response in the Southern Ocean. Article in Journal/Newspaper Southern Ocean BORIS (Bern Open Repository and Information System, University of Bern) Southern Ocean Journal of Climate 20 24 5912 5928 |
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Open Polar |
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BORIS (Bern Open Repository and Information System, University of Bern) |
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ftunivbern |
language |
English |
topic |
530 Physics |
spellingShingle |
530 Physics Stocker, Thomas F. Timmermann, Axel Renold, Manuel Timm, Oliver Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation |
topic_facet |
530 Physics |
description |
Freshwater hosing experiments with a comprehensive coupled climate model and a coupled model of intermediate complexity are performed with and without global salt compensation in order to investigate the robustness of the bipolar seesaw. In both cases, a strong reduction of the Atlantic meridional overturning circulation is induced, and a warming in the South Atlantic results. When a globally uniform salt flux is applied at the surface in order to keep the global mean salinity constant, this causes additional widespread warming in the Southern Ocean. It is shown that this warming is mainly due to heat transport anomalies that are induced by the specific parameterization in ocean models to represent eddy mixing. Surface salt fluxes tend to move outcropping isopycnals equatorward. As the density perturbation originates at the surface, changes in isopycnal slopes are generated that lead to anomalies in the bolus velocity field. The associated bolus heat flux convergence creates a warming enhancing the bipolar seesaw response, particularly in the Southern Ocean. The importance of this mechanism is illustrated in coupled model simulations in which this parameterization in the ocean model component is switched on or off. Additional experiments in which the same total amount of freshwater is delivered at rates 10 times smaller show that the effect of the global salt compensation is not important in this case, but that the eddy-mixing parameterization is still responsible for a substantial temperature response in the Southern Ocean. |
format |
Article in Journal/Newspaper |
author |
Stocker, Thomas F. Timmermann, Axel Renold, Manuel Timm, Oliver |
author_facet |
Stocker, Thomas F. Timmermann, Axel Renold, Manuel Timm, Oliver |
author_sort |
Stocker, Thomas F. |
title |
Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation |
title_short |
Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation |
title_full |
Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation |
title_fullStr |
Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation |
title_full_unstemmed |
Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation |
title_sort |
effects of salt compensation on the climate model response in simulations of large changes of the atlantic meridional overturning circulation |
publisher |
American Meteorological Society |
publishDate |
2007 |
url |
https://boris.unibe.ch/25267/1/2007jcli1662%252E1.pdf https://boris.unibe.ch/25267/ |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Stocker, Thomas F.; Timmermann, Axel; Renold, Manuel; Timm, Oliver (2007). Effects of salt compensation on the climate model response in simulations of large changes of the Atlantic meridional overturning circulation. Journal of Climate, 20(24), pp. 5912-5928. American Meteorological Society 10.1175/2007JCLI1662.1 <http://dx.doi.org/10.1175/2007JCLI1662.1> |
op_relation |
https://boris.unibe.ch/25267/ |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1175/2007JCLI1662.1 |
container_title |
Journal of Climate |
container_volume |
20 |
container_issue |
24 |
container_start_page |
5912 |
op_container_end_page |
5928 |
_version_ |
1774723686438273024 |