The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation
Published reconstructions of radiocarbon in the Atlantic sector of the Southern Ocean indicate that there is a mid-depth maximum in radiocarbon age during the last glacial maximum (LGM). This is in contrast to the modern ocean where intense mixing between water masses results in a relatively homogen...
Published in: | Paleoceanography |
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Language: | English |
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2015
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Online Access: | https://research-portal.st-andrews.ac.uk/en/publications/2d6fd527-fc89-4086-b792-e9234ef5fb01 https://doi.org/10.1002/2015PA002778 https://research-repository.st-andrews.ac.uk/bitstream/10023/8088/1/Burke_2015_Paleo_Glacial.pdf http://onlinelibrary.wiley.com/doi/10.1002/2015PA002778/full#footer-support-info |
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ftunstandrewcris:oai:research-portal.st-andrews.ac.uk:publications/2d6fd527-fc89-4086-b792-e9234ef5fb01 2024-10-20T14:04:53+00:00 The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation Burke, Andrea Stewart, Andrew L. Adkins, Jess F. Ferrari, Raffaele Jansen, Mate F. Thompson, Andrew F. 2015 application/pdf https://research-portal.st-andrews.ac.uk/en/publications/2d6fd527-fc89-4086-b792-e9234ef5fb01 https://doi.org/10.1002/2015PA002778 https://research-repository.st-andrews.ac.uk/bitstream/10023/8088/1/Burke_2015_Paleo_Glacial.pdf http://onlinelibrary.wiley.com/doi/10.1002/2015PA002778/full#footer-support-info eng eng info:eu-repo/semantics/openAccess Burke , A , Stewart , A L , Adkins , J F , Ferrari , R , Jansen , M F & Thompson , A F 2015 , ' The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation ' , Paleoceanography , vol. Early view . https://doi.org/10.1002/2015PA002778 Radiocarbon Overturning circulation Last Glacial Maximum article 2015 ftunstandrewcris https://doi.org/10.1002/2015PA002778 2024-10-02T23:40:44Z Published reconstructions of radiocarbon in the Atlantic sector of the Southern Ocean indicate that there is a mid-depth maximum in radiocarbon age during the last glacial maximum (LGM). This is in contrast to the modern ocean where intense mixing between water masses results in a relatively homogenous radiocarbon profile. Ferrari et al. [2014] suggested that the extended Antarctic sea ice cover during the LGM necessitated a shallower boundary between the upper and lower branches of the meridional overturning circulation (MOC). This shoaled boundary lay above major topographic features associated with strong diapycnal mixing, isolating dense southern-sourced water in the lower branch of the overturning circulation. This isolation would have allowed radiocarbon to decay, and thus provides a possible explanation for the mid-depth radiocarbon age bulge. We test this hypothesis using an idealized, 2D, residual-mean dynamical model of the global overturning circulation. Concentration distributions of a decaying tracer that is advected by the simulated overturning are compared to published radiocarbon data. We find that a 600 km (~5° of latitude) increase in sea ice extent shoals the boundary between the upper and lower branches of the overturning circulation at 45°S by 600 m, and shoals the depth of North Atlantic Deep Water (NADW) convection at 50°N by 2500 m. This change in circulation configuration alone decreases the radiocarbon content in the mid-depth South Atlantic at 45°S by 40‰, even without an increase in surface radiocarbon age in the source region of deep waters during the LGM. Article in Journal/Newspaper Antarc* Antarctic NADW North Atlantic Deep Water North Atlantic Sea ice Southern Ocean University of St Andrews: Research Portal Antarctic Southern Ocean Paleoceanography 30 7 1021 1039 |
institution |
Open Polar |
collection |
University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
topic |
Radiocarbon Overturning circulation Last Glacial Maximum |
spellingShingle |
Radiocarbon Overturning circulation Last Glacial Maximum Burke, Andrea Stewart, Andrew L. Adkins, Jess F. Ferrari, Raffaele Jansen, Mate F. Thompson, Andrew F. The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation |
topic_facet |
Radiocarbon Overturning circulation Last Glacial Maximum |
description |
Published reconstructions of radiocarbon in the Atlantic sector of the Southern Ocean indicate that there is a mid-depth maximum in radiocarbon age during the last glacial maximum (LGM). This is in contrast to the modern ocean where intense mixing between water masses results in a relatively homogenous radiocarbon profile. Ferrari et al. [2014] suggested that the extended Antarctic sea ice cover during the LGM necessitated a shallower boundary between the upper and lower branches of the meridional overturning circulation (MOC). This shoaled boundary lay above major topographic features associated with strong diapycnal mixing, isolating dense southern-sourced water in the lower branch of the overturning circulation. This isolation would have allowed radiocarbon to decay, and thus provides a possible explanation for the mid-depth radiocarbon age bulge. We test this hypothesis using an idealized, 2D, residual-mean dynamical model of the global overturning circulation. Concentration distributions of a decaying tracer that is advected by the simulated overturning are compared to published radiocarbon data. We find that a 600 km (~5° of latitude) increase in sea ice extent shoals the boundary between the upper and lower branches of the overturning circulation at 45°S by 600 m, and shoals the depth of North Atlantic Deep Water (NADW) convection at 50°N by 2500 m. This change in circulation configuration alone decreases the radiocarbon content in the mid-depth South Atlantic at 45°S by 40‰, even without an increase in surface radiocarbon age in the source region of deep waters during the LGM. |
format |
Article in Journal/Newspaper |
author |
Burke, Andrea Stewart, Andrew L. Adkins, Jess F. Ferrari, Raffaele Jansen, Mate F. Thompson, Andrew F. |
author_facet |
Burke, Andrea Stewart, Andrew L. Adkins, Jess F. Ferrari, Raffaele Jansen, Mate F. Thompson, Andrew F. |
author_sort |
Burke, Andrea |
title |
The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation |
title_short |
The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation |
title_full |
The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation |
title_fullStr |
The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation |
title_full_unstemmed |
The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation |
title_sort |
glacial mid-depth radiocarbon bulge and its implications for the overturning circulation |
publishDate |
2015 |
url |
https://research-portal.st-andrews.ac.uk/en/publications/2d6fd527-fc89-4086-b792-e9234ef5fb01 https://doi.org/10.1002/2015PA002778 https://research-repository.st-andrews.ac.uk/bitstream/10023/8088/1/Burke_2015_Paleo_Glacial.pdf http://onlinelibrary.wiley.com/doi/10.1002/2015PA002778/full#footer-support-info |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic NADW North Atlantic Deep Water North Atlantic Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic NADW North Atlantic Deep Water North Atlantic Sea ice Southern Ocean |
op_source |
Burke , A , Stewart , A L , Adkins , J F , Ferrari , R , Jansen , M F & Thompson , A F 2015 , ' The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation ' , Paleoceanography , vol. Early view . https://doi.org/10.1002/2015PA002778 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1002/2015PA002778 |
container_title |
Paleoceanography |
container_volume |
30 |
container_issue |
7 |
container_start_page |
1021 |
op_container_end_page |
1039 |
_version_ |
1813453732412653568 |