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The modern and glacial overturning circulation in the Atlantic ocean in PMIP coupled model simulations

The modern and glacial overturning circulation in the Atlantic ocean in PMIP coupled model simulations
The modern and glacial overturning circulation in the Atlantic ocean in PMIP coupled model simulations
This study analyses the response of the Atlantic meridional overturning circulation (AMOC) to LGM forcings and boundary conditions in nine PMIP coupled model simulations, including both GCMs and Earth system Models of Intermediate Complexity. Model results differ widely. The AMOC slows down considerably (by 20–40%) during the LGM as compared to the modern climate in four models, there is a slight reduction in one model and four models show a substantial increase in AMOC strength (by 10–40%). It is found that a major controlling factor for the AMOC response is the density contrast between Antarctic Bottom Water (AABW) and North Atlantic Deep Water (NADW) at their source regions. Changes in the density contrast are determined by the opposing effects of changes in temperature and salinity, with more saline AABW as compared to NADW consistently found in all models and less cooling of AABW in all models but one. In only two models is the AMOC response during the LGM directly related to the response in net evaporation over the Atlantic basin. Most models show large changes in the ocean freshwater transports into the basin, but this does not seem to affect the AMOC response. Finally, there is some dependence on the accuracy of the control state.
1814-9332
51-64
Weber, S.L.
6d40758d-ce76-4faa-b8a9-727ca6189a10
Drijfhout, S.S.
a5c76079-179b-490c-93fe-fc0391aacf13
Abe-Ouchi, A.
292b04f5-70d4-49a3-a651-c0a5ee0d82dc
Crucifix, M.
12be08bf-fbeb-4657-abf2-09d55a18bd2f
Eby, M.
a1c169fd-8ccd-428f-a405-aa1650738543
Ganopolski, A.
cbaa7875-b285-420d-8515-8410dc2a0053
Murakami, S.
843b6fe9-ea36-45dd-8a45-e9b790e8deaa
Otto-Bliesner, B.
65274d5a-3184-48c7-a3c0-e5ee49d5539d
Peltier, W.R.
a2d5d052-559e-42ac-9ae7-5c8888576ca7
Weber, S.L.
6d40758d-ce76-4faa-b8a9-727ca6189a10
Drijfhout, S.S.
a5c76079-179b-490c-93fe-fc0391aacf13
Abe-Ouchi, A.
292b04f5-70d4-49a3-a651-c0a5ee0d82dc
Crucifix, M.
12be08bf-fbeb-4657-abf2-09d55a18bd2f
Eby, M.
a1c169fd-8ccd-428f-a405-aa1650738543
Ganopolski, A.
cbaa7875-b285-420d-8515-8410dc2a0053
Murakami, S.
843b6fe9-ea36-45dd-8a45-e9b790e8deaa
Otto-Bliesner, B.
65274d5a-3184-48c7-a3c0-e5ee49d5539d
Peltier, W.R.
a2d5d052-559e-42ac-9ae7-5c8888576ca7

Weber, S.L., Drijfhout, S.S., Abe-Ouchi, A., Crucifix, M., Eby, M., Ganopolski, A., Murakami, S., Otto-Bliesner, B. and Peltier, W.R. (2007) The modern and glacial overturning circulation in the Atlantic ocean in PMIP coupled model simulations. Climate of the Past, 3 (1), 51-64. (doi:10.5194/cp-3-51-2007).

Record type: Article

Abstract

This study analyses the response of the Atlantic meridional overturning circulation (AMOC) to LGM forcings and boundary conditions in nine PMIP coupled model simulations, including both GCMs and Earth system Models of Intermediate Complexity. Model results differ widely. The AMOC slows down considerably (by 20–40%) during the LGM as compared to the modern climate in four models, there is a slight reduction in one model and four models show a substantial increase in AMOC strength (by 10–40%). It is found that a major controlling factor for the AMOC response is the density contrast between Antarctic Bottom Water (AABW) and North Atlantic Deep Water (NADW) at their source regions. Changes in the density contrast are determined by the opposing effects of changes in temperature and salinity, with more saline AABW as compared to NADW consistently found in all models and less cooling of AABW in all models but one. In only two models is the AMOC response during the LGM directly related to the response in net evaporation over the Atlantic basin. Most models show large changes in the ocean freshwater transports into the basin, but this does not seem to affect the AMOC response. Finally, there is some dependence on the accuracy of the control state.

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Published date: 2007
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 349156
URI: http://eprints.soton.ac.uk/id/eprint/349156
ISSN: 1814-9332
PURE UUID: 9100f53b-8c15-474a-935e-d7c58b066d48

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Date deposited: 26 Feb 2013 10:51
Last modified: 08 Jan 2022 17:58

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Contributors

Author: S.L. Weber
Author: S.S. Drijfhout
Author: A. Abe-Ouchi
Author: M. Crucifix
Author: M. Eby
Author: A. Ganopolski
Author: S. Murakami
Author: B. Otto-Bliesner
Author: W.R. Peltier

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