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Changes in the strength of the Nordic Seas Overflows over the past 3000 years

Moffa-Sanchez, P; Hall, IR; Thornalley, DJR; Barker, S; Stewart, C; (2015) Changes in the strength of the Nordic Seas Overflows over the past 3000 years. Quaternary Science Reviews , 123 pp. 134-143. 10.1016/j.quascirev.2015.06.007. Green open access

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Abstract

The Nordic Seas Overflows constitute the densest component of the deep limb of the Atlantic Meridional Overturning Circulation (AMOC). Changes in the vigour of the overflows may have had important climatic effects in the past and may also have in the future. Yet, evidence for multidecadal to millennial changes in the deep limb of the AMOC and their potential relationship to North Atlantic climate variability during the Holocene remains weakly constrained. Here we present grain size data, as a proxy for near-bottom current speed, from sub-decadal to decadally resolved sediment cores located in the direct pathway of the two Nordic Overflows east and west of Iceland, the Iceland-Scotland Overflow Water (ISOW) and the Denmark Strait Overflow Water (DSOW), respectively. The results show no clear relationship between reconstructed changes in the vigour of the Nordic Overflows and the well-known periods of centennial-scale climate variability recorded in the North Atlantic region. However, well-defined millennial-scale trends are found in both of the overflow strength records over the last 3000 years, which were possibly related to hydrographic reorganizations in the Nordic Seas, driven by the decrease in Northern Hemisphere summer insolation over the Neoglacial period. A comparison between the near-bottom flow speed reconstructions from ISOW and DSOW suggests an anti-phased relationship between the Nordic Seas Overflows east and west of Iceland over the last 3000 years. This feature has been observed in climate models potentially as a result of shifts in the deep water formation sites as a response to changes in atmospheric patterns over the Nordic Seas.

Type: Article
Title: Changes in the strength of the Nordic Seas Overflows over the past 3000 years
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.quascirev.2015.06.007
Publisher version: http://dx.doi.org/10.1016/j.astropartphys.2015.04....
Language: English
Additional information: Copyright © 2015. This manuscript version is published under a Creative Commons Attribution Non-commercial Non-derivative 4.0 International licence (CC BY-NC-ND 4.0). This licence allows you to share, copy, distribute and transmit the work for personal and non-commercial use providing author and publisher attribution is clearly stated. Further details about CC BY licences are available at http://creativecommons.org/licenses/by/4.0. Access may be initially restricted by the publisher.
Keywords: Physical, geosciences, multidisciplinary, physical geography, geology, late Holocene, North Atlantic, Nordic Overflows, paleoceanography, Denmark strait overflow, Faroe-Bank Channel, Greenland-Scotland ridge, surface temperature variability, North-Atlantic oscillation, revised circulation scheme, Western Boundary current, deep-water, oceanographic variability, Icelandic shelf
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography
URI: https://discovery.ucl.ac.uk/id/eprint/1499144
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