On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater
The thermohaline circulation (THC) and the oceanic heat and freshwater transports are essential for understanding the global climate system. Streamfunctions are widely used in oceanography to represent the THC and estimate the transport of heat and freshwater. In the present study, the regional and...
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Copernicus Publications
2014
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00018405 2023-05-15T13:41:02+02:00 On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater Ballarotta, M. Falahat, S. Brodeau, L. Döös, K. 2014-11 electronic https://doi.org/10.5194/os-10-907-2014 https://noa.gwlb.de/receive/cop_mods_00018405 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00018360/os-10-907-2014.pdf https://os.copernicus.org/articles/10/907/2014/os-10-907-2014.pdf eng eng Copernicus Publications Ocean Science -- http://www.bibliothek.uni-regensburg.de/ezeit/?2183769 -- http://www.copernicus.org/EGU/os/os.html -- 1812-0792 https://doi.org/10.5194/os-10-907-2014 https://noa.gwlb.de/receive/cop_mods_00018405 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00018360/os-10-907-2014.pdf https://os.copernicus.org/articles/10/907/2014/os-10-907-2014.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2014 ftnonlinearchiv https://doi.org/10.5194/os-10-907-2014 2022-02-08T22:53:10Z The thermohaline circulation (THC) and the oceanic heat and freshwater transports are essential for understanding the global climate system. Streamfunctions are widely used in oceanography to represent the THC and estimate the transport of heat and freshwater. In the present study, the regional and global changes of the THC, the transports of heat and freshwater and the timescale of the circulation between the Last Glacial Maximum (LGM, ≈ 21 kyr ago) and the present-day climate are explored using an Ocean General Circulation Model and streamfunctions projected in various coordinate systems. We found that the LGM tropical circulation is about 10% stronger than under modern conditions due to stronger wind stress. Consequently, the maximum tropical transport of heat is about 20% larger during the LGM. In the North Atlantic basin, the large sea-ice extent during the LGM constrains the Gulf Stream to propagate in a more zonal direction, reducing the transport of heat towards high latitudes by almost 50% and reorganising the freshwater transport. The strength of the Atlantic Meridional Overturning Circulation depends strongly on the coordinate system. It varies between 9 and 16 Sv during the LGM, and between 12 to 19 Sv for the present day. Similar to paleo-proxy reconstructions, a large intrusion of saline Antarctic Bottom Water takes place into the Northern Hemisphere basins and squeezes most of the Conveyor Belt circulation into a shallower part of the ocean. These different haline regimes between the glacial and interglacial period are illustrated by the streamfunctions in latitude–salinity coordinates and thermohaline coordinates. From these diagnostics, we found that the LGM Conveyor Belt circulation is driven by an enhanced salinity contrast between the Atlantic and the Pacific basin. The LGM abyssal circulation lifts and makes the Conveyor Belt cell deviate from the abyssal region, resulting in a ventilated upper layer above a deep stagnant layer, and an Atlantic circulation more isolated from the Pacific. An estimate of the timescale of the circulation reveals a sluggish abyssal circulation during the LGM, and a Conveyor Belt circulation that is more vigorous due to the combination of a stronger wind stress and a shortened circulation route. Article in Journal/Newspaper Antarc* Antarctic North Atlantic Sea ice Niedersächsisches Online-Archiv NOA Antarctic Pacific Ocean Science 10 6 907 921 |
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Niedersächsisches Online-Archiv NOA |
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language |
English |
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article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Ballarotta, M. Falahat, S. Brodeau, L. Döös, K. On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater |
topic_facet |
article Verlagsveröffentlichung |
description |
The thermohaline circulation (THC) and the oceanic heat and freshwater transports are essential for understanding the global climate system. Streamfunctions are widely used in oceanography to represent the THC and estimate the transport of heat and freshwater. In the present study, the regional and global changes of the THC, the transports of heat and freshwater and the timescale of the circulation between the Last Glacial Maximum (LGM, ≈ 21 kyr ago) and the present-day climate are explored using an Ocean General Circulation Model and streamfunctions projected in various coordinate systems. We found that the LGM tropical circulation is about 10% stronger than under modern conditions due to stronger wind stress. Consequently, the maximum tropical transport of heat is about 20% larger during the LGM. In the North Atlantic basin, the large sea-ice extent during the LGM constrains the Gulf Stream to propagate in a more zonal direction, reducing the transport of heat towards high latitudes by almost 50% and reorganising the freshwater transport. The strength of the Atlantic Meridional Overturning Circulation depends strongly on the coordinate system. It varies between 9 and 16 Sv during the LGM, and between 12 to 19 Sv for the present day. Similar to paleo-proxy reconstructions, a large intrusion of saline Antarctic Bottom Water takes place into the Northern Hemisphere basins and squeezes most of the Conveyor Belt circulation into a shallower part of the ocean. These different haline regimes between the glacial and interglacial period are illustrated by the streamfunctions in latitude–salinity coordinates and thermohaline coordinates. From these diagnostics, we found that the LGM Conveyor Belt circulation is driven by an enhanced salinity contrast between the Atlantic and the Pacific basin. The LGM abyssal circulation lifts and makes the Conveyor Belt cell deviate from the abyssal region, resulting in a ventilated upper layer above a deep stagnant layer, and an Atlantic circulation more isolated from the Pacific. An estimate of the timescale of the circulation reveals a sluggish abyssal circulation during the LGM, and a Conveyor Belt circulation that is more vigorous due to the combination of a stronger wind stress and a shortened circulation route. |
format |
Article in Journal/Newspaper |
author |
Ballarotta, M. Falahat, S. Brodeau, L. Döös, K. |
author_facet |
Ballarotta, M. Falahat, S. Brodeau, L. Döös, K. |
author_sort |
Ballarotta, M. |
title |
On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater |
title_short |
On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater |
title_full |
On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater |
title_fullStr |
On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater |
title_full_unstemmed |
On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater |
title_sort |
on the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/os-10-907-2014 https://noa.gwlb.de/receive/cop_mods_00018405 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00018360/os-10-907-2014.pdf https://os.copernicus.org/articles/10/907/2014/os-10-907-2014.pdf |
geographic |
Antarctic Pacific |
geographic_facet |
Antarctic Pacific |
genre |
Antarc* Antarctic North Atlantic Sea ice |
genre_facet |
Antarc* Antarctic North Atlantic Sea ice |
op_relation |
Ocean Science -- http://www.bibliothek.uni-regensburg.de/ezeit/?2183769 -- http://www.copernicus.org/EGU/os/os.html -- 1812-0792 https://doi.org/10.5194/os-10-907-2014 https://noa.gwlb.de/receive/cop_mods_00018405 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00018360/os-10-907-2014.pdf https://os.copernicus.org/articles/10/907/2014/os-10-907-2014.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/os-10-907-2014 |
container_title |
Ocean Science |
container_volume |
10 |
container_issue |
6 |
container_start_page |
907 |
op_container_end_page |
921 |
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1766144916779433984 |