Variations of the Atlantic meridional overturning circulation in control and transient simulations of the last millennium

The variability of the Atlantic meridional overturing circulation (AMOC) strength is investigated in control experiments and in transient simulations of up to the last millennium using the low-resolution Community Climate System Model version 3. In the transient simulations the AMOC exhibits enhance...

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Published in:Climate of the Past
Main Authors: D. Hofer, C. C. Raible, T. F. Stocker
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2011
Subjects:
Online Access:https://doi.org/10.5194/cp-7-133-2011
https://doaj.org/article/1728ce7f4aa44743a1e990b574088235
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spelling ftdoajarticles:oai:doaj.org/article:1728ce7f4aa44743a1e990b574088235 2023-05-15T16:30:04+02:00 Variations of the Atlantic meridional overturning circulation in control and transient simulations of the last millennium D. Hofer C. C. Raible T. F. Stocker 2011-02-01T00:00:00Z https://doi.org/10.5194/cp-7-133-2011 https://doaj.org/article/1728ce7f4aa44743a1e990b574088235 EN eng Copernicus Publications http://www.clim-past.net/7/133/2011/cp-7-133-2011.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 doi:10.5194/cp-7-133-2011 1814-9324 1814-9332 https://doaj.org/article/1728ce7f4aa44743a1e990b574088235 Climate of the Past, Vol 7, Iss 1, Pp 133-150 (2011) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2011 ftdoajarticles https://doi.org/10.5194/cp-7-133-2011 2022-12-31T00:13:50Z The variability of the Atlantic meridional overturing circulation (AMOC) strength is investigated in control experiments and in transient simulations of up to the last millennium using the low-resolution Community Climate System Model version 3. In the transient simulations the AMOC exhibits enhanced low-frequency variability that is mainly caused by infrequent transitions between two semi-stable circulation states which amount to a 10 percent change of the maximum overturning. One transition is also found in a control experiment, but the time-varying external forcing significantly increases the probability of the occurrence of such events though not having a direct, linear impact on the AMOC. The transition from a high to a low AMOC state starts with a reduction of the convection in the Labrador and Irminger Seas and goes along with a changed barotropic circulation of both gyres in the North Atlantic and a gradual strengthening of the convection in the Greenland-Iceland-Norwegian (GIN) Seas. In contrast, the transition from a weak to a strong overturning is induced by decreased mixing in the GIN Seas. As a consequence of the transition, regional sea surface temperature (SST) anomalies are found in the midlatitude North Atlantic and in the convection regions with an amplitude of up to 3 K. The atmospheric response to the SST forcing associated with the transition indicates a significant impact on the Scandinavian surface air temperature (SAT) in the order of 1 K. Thus, the changes of the ocean circulation make a major contribution to the Scandinavian SAT variability in the last millennium. Article in Journal/Newspaper Greenland Iceland North Atlantic Directory of Open Access Journals: DOAJ Articles Greenland Climate of the Past 7 1 133 150
institution Open Polar
collection Directory of Open Access Journals: DOAJ Articles
op_collection_id ftdoajarticles
language English
topic Environmental pollution
TD172-193.5
Environmental protection
TD169-171.8
Environmental sciences
GE1-350
spellingShingle Environmental pollution
TD172-193.5
Environmental protection
TD169-171.8
Environmental sciences
GE1-350
D. Hofer
C. C. Raible
T. F. Stocker
Variations of the Atlantic meridional overturning circulation in control and transient simulations of the last millennium
topic_facet Environmental pollution
TD172-193.5
Environmental protection
TD169-171.8
Environmental sciences
GE1-350
description The variability of the Atlantic meridional overturing circulation (AMOC) strength is investigated in control experiments and in transient simulations of up to the last millennium using the low-resolution Community Climate System Model version 3. In the transient simulations the AMOC exhibits enhanced low-frequency variability that is mainly caused by infrequent transitions between two semi-stable circulation states which amount to a 10 percent change of the maximum overturning. One transition is also found in a control experiment, but the time-varying external forcing significantly increases the probability of the occurrence of such events though not having a direct, linear impact on the AMOC. The transition from a high to a low AMOC state starts with a reduction of the convection in the Labrador and Irminger Seas and goes along with a changed barotropic circulation of both gyres in the North Atlantic and a gradual strengthening of the convection in the Greenland-Iceland-Norwegian (GIN) Seas. In contrast, the transition from a weak to a strong overturning is induced by decreased mixing in the GIN Seas. As a consequence of the transition, regional sea surface temperature (SST) anomalies are found in the midlatitude North Atlantic and in the convection regions with an amplitude of up to 3 K. The atmospheric response to the SST forcing associated with the transition indicates a significant impact on the Scandinavian surface air temperature (SAT) in the order of 1 K. Thus, the changes of the ocean circulation make a major contribution to the Scandinavian SAT variability in the last millennium.
format Article in Journal/Newspaper
author D. Hofer
C. C. Raible
T. F. Stocker
author_facet D. Hofer
C. C. Raible
T. F. Stocker
author_sort D. Hofer
title Variations of the Atlantic meridional overturning circulation in control and transient simulations of the last millennium
title_short Variations of the Atlantic meridional overturning circulation in control and transient simulations of the last millennium
title_full Variations of the Atlantic meridional overturning circulation in control and transient simulations of the last millennium
title_fullStr Variations of the Atlantic meridional overturning circulation in control and transient simulations of the last millennium
title_full_unstemmed Variations of the Atlantic meridional overturning circulation in control and transient simulations of the last millennium
title_sort variations of the atlantic meridional overturning circulation in control and transient simulations of the last millennium
publisher Copernicus Publications
publishDate 2011
url https://doi.org/10.5194/cp-7-133-2011
https://doaj.org/article/1728ce7f4aa44743a1e990b574088235
geographic Greenland
geographic_facet Greenland
genre Greenland
Iceland
North Atlantic
genre_facet Greenland
Iceland
North Atlantic
op_source Climate of the Past, Vol 7, Iss 1, Pp 133-150 (2011)
op_relation http://www.clim-past.net/7/133/2011/cp-7-133-2011.pdf
https://doaj.org/toc/1814-9324
https://doaj.org/toc/1814-9332
doi:10.5194/cp-7-133-2011
1814-9324
1814-9332
https://doaj.org/article/1728ce7f4aa44743a1e990b574088235
op_doi https://doi.org/10.5194/cp-7-133-2011
container_title Climate of the Past
container_volume 7
container_issue 1
container_start_page 133
op_container_end_page 150
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