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dc.contributor.authorBurke, Andrea
dc.contributor.authorStewart, Andrew L.
dc.contributor.authorAdkins, Jess F.
dc.contributor.authorFerrari, Raffaele
dc.contributor.authorJansen, Mate F.
dc.contributor.authorThompson, Andrew F.
dc.identifier.citationBurke , 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 .
dc.identifier.otherORCID: /0000-0002-3754-1498/work/64034538
dc.descriptionThis 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.en
dc.description.abstractPublished 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.
dc.subjectOverturning circulationen
dc.subjectLast Glacial Maximumen
dc.subjectGB Physical geographyen
dc.titleThe glacial mid-depth radiocarbon bulge and its implications for the overturning circulationen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. Earth and Environmental Sciencesen
dc.contributor.institutionUniversity of St Andrews. St Andrews Isotope Geochemistryen
dc.description.statusPeer revieweden

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