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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Published in:Ocean Science
Main Authors: Ballarotta, Maxime, Falahat, Saeed, Brodeau, Laurent, Döös, Kristofer
Format: Article in Journal/Newspaper
Language:English
Published: Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK) 2014
Subjects:
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-109383
https://doi.org/10.5194/os-10-907-2014
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spelling ftstockholmuniv:oai:DiVA.org:su-109383 2023-05-15T13:56:08+02:00 On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater Ballarotta, Maxime Falahat, Saeed Brodeau, Laurent Döös, Kristofer 2014 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-109383 https://doi.org/10.5194/os-10-907-2014 eng eng Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK) Stockholms universitet, Meteorologiska institutionen (MISU) Gottingen : Copernicus Publications Ocean Science, 1812-0784, 2014, 10:6, s. 907-921 orcid:0000-0001-8745-7510 orcid:0000-0002-1309-5921 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-109383 doi:10.5194/os-10-907-2014 ISI:000347475600003 info:eu-repo/semantics/openAccess Thermohaline circulation glacial interglacial model Oceanography Hydrology and Water Resources Oceanografi hydrologi och vattenresurser Article in journal info:eu-repo/semantics/article text 2014 ftstockholmuniv https://doi.org/10.5194/os-10-907-2014 2023-02-23T21:43:26Z 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 ... Article in Journal/Newspaper Antarc* Antarctic North Atlantic Sea ice Stockholm University: Publications (DiVA) Antarctic Pacific Ocean Science 10 6 907 921
institution Open Polar
collection Stockholm University: Publications (DiVA)
op_collection_id ftstockholmuniv
language English
topic Thermohaline circulation
glacial
interglacial
model
Oceanography
Hydrology and Water Resources
Oceanografi
hydrologi och vattenresurser
spellingShingle Thermohaline circulation
glacial
interglacial
model
Oceanography
Hydrology and Water Resources
Oceanografi
hydrologi och vattenresurser
Ballarotta, Maxime
Falahat, Saeed
Brodeau, Laurent
Döös, Kristofer
On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater
topic_facet Thermohaline circulation
glacial
interglacial
model
Oceanography
Hydrology and Water Resources
Oceanografi
hydrologi och vattenresurser
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 ...
format Article in Journal/Newspaper
author Ballarotta, Maxime
Falahat, Saeed
Brodeau, Laurent
Döös, Kristofer
author_facet Ballarotta, Maxime
Falahat, Saeed
Brodeau, Laurent
Döös, Kristofer
author_sort Ballarotta, Maxime
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 Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK)
publishDate 2014
url http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-109383
https://doi.org/10.5194/os-10-907-2014
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, 1812-0784, 2014, 10:6, s. 907-921
orcid:0000-0001-8745-7510
orcid:0000-0002-1309-5921
http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-109383
doi:10.5194/os-10-907-2014
ISI:000347475600003
op_rights 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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