The glacial mid-depth radiocarbon bulge and its implications for the overturning circulation
This work was supported by a Foster and Coco Stanback Postdoctoral Fellowship and a Marie Curie Career Integration grant (CIG14-631752) awarded to A.B., and an NSF grant awarded to A.F.T. Published reconstructions of radiocarbon in the Atlantic sector of the Southern Ocean indicate that there is a m...
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ftstandrewserep:oai:research-repository.st-andrews.ac.uk:10023/8088 2024-04-28T07:59:54+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. NERC University of St Andrews. Earth and Environmental Sciences University of St Andrews. St Andrews Isotope Geochemistry 2016-01-27 3140497 application/pdf https://hdl.handle.net/10023/8088 https://doi.org/10.1002/2015PA002778 http://onlinelibrary.wiley.com/doi/10.1002/2015PA002778/full#footer-support-info eng eng Paleoceanography 192381923 2d6fd527-fc89-4086-b792-e9234ef5fb01 84939252669 000360058100015 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 0883-8305 ORCID: /0000-0002-3754-1498/work/64034538 https://hdl.handle.net/10023/8088 doi:10.1002/2015PA002778 http://onlinelibrary.wiley.com/doi/10.1002/2015PA002778/full#footer-support-info NE/M004619/1 Radiocarbon Overturning circulation Last Glacial Maximum GB Physical geography 3rd-DAS GB Journal article 2016 ftstandrewserep https://doi.org/10.1002/2015PA002778 2024-04-09T23:33:08Z This work was supported by a Foster and Coco Stanback Postdoctoral Fellowship and a Marie Curie Career Integration grant (CIG14-631752) awarded to A.B., and an NSF grant awarded to A.F.T. 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. Peer reviewed Article in Journal/Newspaper Antarc* Antarctic NADW North Atlantic Deep Water North Atlantic Sea ice Southern Ocean University of St Andrews: Digital Research Repository Paleoceanography 30 7 1021 1039 |
institution |
Open Polar |
collection |
University of St Andrews: Digital Research Repository |
op_collection_id |
ftstandrewserep |
language |
English |
topic |
Radiocarbon Overturning circulation Last Glacial Maximum GB Physical geography 3rd-DAS GB |
spellingShingle |
Radiocarbon Overturning circulation Last Glacial Maximum GB Physical geography 3rd-DAS GB 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 GB Physical geography 3rd-DAS GB |
description |
This work was supported by a Foster and Coco Stanback Postdoctoral Fellowship and a Marie Curie Career Integration grant (CIG14-631752) awarded to A.B., and an NSF grant awarded to A.F.T. 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. Peer reviewed |
author2 |
NERC University of St Andrews. Earth and Environmental Sciences University of St Andrews. St Andrews Isotope Geochemistry |
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 |
2016 |
url |
https://hdl.handle.net/10023/8088 https://doi.org/10.1002/2015PA002778 http://onlinelibrary.wiley.com/doi/10.1002/2015PA002778/full#footer-support-info |
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_relation |
Paleoceanography 192381923 2d6fd527-fc89-4086-b792-e9234ef5fb01 84939252669 000360058100015 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 0883-8305 ORCID: /0000-0002-3754-1498/work/64034538 https://hdl.handle.net/10023/8088 doi:10.1002/2015PA002778 http://onlinelibrary.wiley.com/doi/10.1002/2015PA002778/full#footer-support-info NE/M004619/1 |
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 |
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