Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model
Direct observations, satellite measurements and paleo records reveal strong variability in the Atlantic subpolar gyre on various time scales. Here we show that variations of comparable amplitude can only be simulated in a coupled climate model in the proximity of a dynamical threshold. The threshold...
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ftubpotsdam:oai:kobv.de-opus4-uni-potsdam:36403 2024-04-21T08:07:34+00:00 Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model Mengel, Matthias Levermann, Anders (Prof. Dr.) Schleussner, Carl-Friedrich Born, Andreas 2012 https://publishup.uni-potsdam.de/frontdoor/index/index/docId/36403 https://doi.org/10.5194/esd-3-189-2012 eng eng https://publishup.uni-potsdam.de/frontdoor/index/index/docId/36403 https://doi.org/10.5194/esd-3-189-2012 info:eu-repo/semantics/closedAccess Institut für Physik und Astronomie article doc-type:article 2012 ftubpotsdam https://doi.org/10.5194/esd-3-189-2012 2024-03-27T15:02:48Z Direct observations, satellite measurements and paleo records reveal strong variability in the Atlantic subpolar gyre on various time scales. Here we show that variations of comparable amplitude can only be simulated in a coupled climate model in the proximity of a dynamical threshold. The threshold and the associated dynamic response is due to a positive feedback involving increased salt transport in the subpolar gyre and enhanced deep convection in its centre. A series of sensitivity experiments is performed with a coarse resolution ocean general circulation model coupled to a statistical-dynamical atmosphere model which in itself does not produce atmospheric variability. To simulate the impact of atmospheric variability, the model system is perturbed with freshwater forcing of varying, but small amplitude and multi-decadal to centennial periodicities and observational variations in wind stress. While both freshwater and wind-stress-forcing have a small direct effect on the strength of the subpolar gyre, the magnitude of the gyre's response is strongly increased in the vicinity of the threshold. Our results indicate that baroclinic self-amplification in the North Atlantic ocean can play an important role in presently observed SPG variability and thereby North Atlantic climate variability on multi-decadal scales. Article in Journal/Newspaper North Atlantic University of Potsdam: publish.UP Earth System Dynamics 3 2 189 197 |
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Open Polar |
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University of Potsdam: publish.UP |
op_collection_id |
ftubpotsdam |
language |
English |
topic |
Institut für Physik und Astronomie |
spellingShingle |
Institut für Physik und Astronomie Mengel, Matthias Levermann, Anders (Prof. Dr.) Schleussner, Carl-Friedrich Born, Andreas Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model |
topic_facet |
Institut für Physik und Astronomie |
description |
Direct observations, satellite measurements and paleo records reveal strong variability in the Atlantic subpolar gyre on various time scales. Here we show that variations of comparable amplitude can only be simulated in a coupled climate model in the proximity of a dynamical threshold. The threshold and the associated dynamic response is due to a positive feedback involving increased salt transport in the subpolar gyre and enhanced deep convection in its centre. A series of sensitivity experiments is performed with a coarse resolution ocean general circulation model coupled to a statistical-dynamical atmosphere model which in itself does not produce atmospheric variability. To simulate the impact of atmospheric variability, the model system is perturbed with freshwater forcing of varying, but small amplitude and multi-decadal to centennial periodicities and observational variations in wind stress. While both freshwater and wind-stress-forcing have a small direct effect on the strength of the subpolar gyre, the magnitude of the gyre's response is strongly increased in the vicinity of the threshold. Our results indicate that baroclinic self-amplification in the North Atlantic ocean can play an important role in presently observed SPG variability and thereby North Atlantic climate variability on multi-decadal scales. |
format |
Article in Journal/Newspaper |
author |
Mengel, Matthias Levermann, Anders (Prof. Dr.) Schleussner, Carl-Friedrich Born, Andreas |
author_facet |
Mengel, Matthias Levermann, Anders (Prof. Dr.) Schleussner, Carl-Friedrich Born, Andreas |
author_sort |
Mengel, Matthias |
title |
Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model |
title_short |
Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model |
title_full |
Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model |
title_fullStr |
Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model |
title_full_unstemmed |
Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model |
title_sort |
enhanced atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model |
publishDate |
2012 |
url |
https://publishup.uni-potsdam.de/frontdoor/index/index/docId/36403 https://doi.org/10.5194/esd-3-189-2012 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://publishup.uni-potsdam.de/frontdoor/index/index/docId/36403 https://doi.org/10.5194/esd-3-189-2012 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.5194/esd-3-189-2012 |
container_title |
Earth System Dynamics |
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3 |
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2 |
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189 |
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197 |
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1796947495296696320 |