The stability of the North Atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model
The stability of the Atlantic thermohaline circulation against meltwater input is investigated in a coupled ocean-atmosphere general circulation model. The meltwater input to the Labrador Sea is increased linearly for 250 years to a maximum input of 0.625 Sv and then reduced again to 0 (both instant...
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ftpubman:oai:pure.mpg.de:item_3025531 2023-08-20T04:02:21+02:00 The stability of the North Atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model Schiller, A. Mikolajewicz, U. Voss, R. 1997 application/pdf http://hdl.handle.net/21.11116/0000-0003-2618-8 http://hdl.handle.net/21.11116/0000-0003-261A-6 http://hdl.handle.net/21.11116/0000-0003-261B-5 eng eng info:eu-repo/semantics/altIdentifier/doi/10.1007/s003820050169 http://hdl.handle.net/21.11116/0000-0003-2618-8 http://hdl.handle.net/21.11116/0000-0003-261A-6 http://hdl.handle.net/21.11116/0000-0003-261B-5 info:eu-repo/semantics/openAccess Climate Dynamics Report / Max-Planck-Institut für Meteorologie info:eu-repo/semantics/article 1997 ftpubman https://doi.org/10.1007/s003820050169 2023-08-01T23:50:02Z The stability of the Atlantic thermohaline circulation against meltwater input is investigated in a coupled ocean-atmosphere general circulation model. The meltwater input to the Labrador Sea is increased linearly for 250 years to a maximum input of 0.625 Sv and then reduced again to 0 (both instantaneously and linearly decreasing over 250 years). The resulting freshening forces a shutdown of the formation of North Atlantic deepwater and a subsequent reversal of the thermohaline circulation of the Atlantic, filling the deep Atlantic with Antarctic bottom water. The change in the overturning pattern causes a drastic reduction of the Atlantic northward heat transport, resulting in a strong cooling with maximum amplitude over the northern North Atlantic and a south-ward shift of the sea-ice margin in the Atlantic. Due to the increased meridional temperature gradient, the intertropical convergence zone over the Atlantic is displaced south-ward and the westerlies in the Northern Hemisphere gain strength. We identify four main feedbacks affecting the stability of the thermohaline circulation: the change in the overturning circulation of the Atlantic leads to longer residence times of the surface water in high-northern latitudes, which allows them to accumulate more precipitation and runoff from the continents. As a consequence the stratification in the North Atlantic becomes more stable. This effect is further amplified by an enhanced northward atmospheric water vapour transport, which increases the freshwater input into the North Atlantic. The reduced northward oceanic heat transport leads to colder seasurface temperatures and an intensification of the atmospheric cyclonic circulation over the Norwegian Sea. The associated Ekman transports cause increased upwelling and increased freshwater export with the East Greenland Current. Both the cooling and the wind-driven circulation changes largely compensate for the effects of the first two feedbacks. The wind-stress feedback destabilizes modes without deep water ... Article in Journal/Newspaper Antarc* Antarctic East Greenland east greenland current Greenland Labrador Sea North Atlantic North atlantic Thermohaline circulation Norwegian Sea Sea ice Max Planck Society: MPG.PuRe Antarctic Greenland Norwegian Sea Climate Dynamics 13 5 325 347 |
institution |
Open Polar |
collection |
Max Planck Society: MPG.PuRe |
op_collection_id |
ftpubman |
language |
English |
description |
The stability of the Atlantic thermohaline circulation against meltwater input is investigated in a coupled ocean-atmosphere general circulation model. The meltwater input to the Labrador Sea is increased linearly for 250 years to a maximum input of 0.625 Sv and then reduced again to 0 (both instantaneously and linearly decreasing over 250 years). The resulting freshening forces a shutdown of the formation of North Atlantic deepwater and a subsequent reversal of the thermohaline circulation of the Atlantic, filling the deep Atlantic with Antarctic bottom water. The change in the overturning pattern causes a drastic reduction of the Atlantic northward heat transport, resulting in a strong cooling with maximum amplitude over the northern North Atlantic and a south-ward shift of the sea-ice margin in the Atlantic. Due to the increased meridional temperature gradient, the intertropical convergence zone over the Atlantic is displaced south-ward and the westerlies in the Northern Hemisphere gain strength. We identify four main feedbacks affecting the stability of the thermohaline circulation: the change in the overturning circulation of the Atlantic leads to longer residence times of the surface water in high-northern latitudes, which allows them to accumulate more precipitation and runoff from the continents. As a consequence the stratification in the North Atlantic becomes more stable. This effect is further amplified by an enhanced northward atmospheric water vapour transport, which increases the freshwater input into the North Atlantic. The reduced northward oceanic heat transport leads to colder seasurface temperatures and an intensification of the atmospheric cyclonic circulation over the Norwegian Sea. The associated Ekman transports cause increased upwelling and increased freshwater export with the East Greenland Current. Both the cooling and the wind-driven circulation changes largely compensate for the effects of the first two feedbacks. The wind-stress feedback destabilizes modes without deep water ... |
format |
Article in Journal/Newspaper |
author |
Schiller, A. Mikolajewicz, U. Voss, R. |
spellingShingle |
Schiller, A. Mikolajewicz, U. Voss, R. The stability of the North Atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model |
author_facet |
Schiller, A. Mikolajewicz, U. Voss, R. |
author_sort |
Schiller, A. |
title |
The stability of the North Atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model |
title_short |
The stability of the North Atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model |
title_full |
The stability of the North Atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model |
title_fullStr |
The stability of the North Atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model |
title_full_unstemmed |
The stability of the North Atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model |
title_sort |
stability of the north atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model |
publishDate |
1997 |
url |
http://hdl.handle.net/21.11116/0000-0003-2618-8 http://hdl.handle.net/21.11116/0000-0003-261A-6 http://hdl.handle.net/21.11116/0000-0003-261B-5 |
geographic |
Antarctic Greenland Norwegian Sea |
geographic_facet |
Antarctic Greenland Norwegian Sea |
genre |
Antarc* Antarctic East Greenland east greenland current Greenland Labrador Sea North Atlantic North atlantic Thermohaline circulation Norwegian Sea Sea ice |
genre_facet |
Antarc* Antarctic East Greenland east greenland current Greenland Labrador Sea North Atlantic North atlantic Thermohaline circulation Norwegian Sea Sea ice |
op_source |
Climate Dynamics Report / Max-Planck-Institut für Meteorologie |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1007/s003820050169 http://hdl.handle.net/21.11116/0000-0003-2618-8 http://hdl.handle.net/21.11116/0000-0003-261A-6 http://hdl.handle.net/21.11116/0000-0003-261B-5 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1007/s003820050169 |
container_title |
Climate Dynamics |
container_volume |
13 |
container_issue |
5 |
container_start_page |
325 |
op_container_end_page |
347 |
_version_ |
1774712766418911232 |