Evaluation of past stratification changes in the Nordic Seas by comparing planktonic foraminiferal δ18O with a solar-forced model

Simstich, Johannes, Lorenz, Stephan J. and Bauch, Henning A. (2012) Evaluation of past stratification changes in the Nordic Seas by comparing planktonic foraminiferal δ18O with a solar-forced model Marine Micropaleontology, 94-95 . pp. 91-96. DOI 10.1016/j.marmicro.2012.06.006.

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Abstract

Density changes in the upper water column of the northern North Atlantic may enhance or reduce vertical convection of surface water with profound effects on meridional overturning and climate in the wider region. This study tests the capability of paired delta O-18 values of two planktonic foraminiferal species - Neogloboquadrina pachyderma (s) and Turborotalita quinqueloba - for the reconstruction of near-surface density stratification in high latitudes or the glacial ocean. Foraminiferal data from two sediment cores of crucial areas of the Nordic Seas were compared with insolation-induced thermal stratification changes as obtained by simulations with the general circulation model ECHO-G. The comparison suggests that insolation was the chief mechanism to change thermocline strength during most of the Holocene. Prior to that, stratification depended by and large on the varying amounts of meltwater injected at the sea surface. Similar to the modern central Arctic Ocean, a pronounced and thick halocline prevented surface waters from deep convection in the central Nordic Seas. Parts of the Norwegian Sea, however, were also stratified but more analogous to the modern Greenland Sea, where deep convection can occur in late winter as a result of the density increase upon a combination of cold temperatures and wind stress. Our findings thus support previous results of an active meridional overturning also in a glacial ocean.

Document Type: Article
Additional Information: WOS:000308904800008
Keywords: Planktonic foraminifera; Nordic Seas; Stable isotopes; Stratification; RADIOCARBON AGE CALIBRATION; LAST-GLACIAL-MAXIMUM; CAL KYR BP; NEOGLOBOQUADRINA-PACHYDERMA; SURFACE CONDITIONS; OCEAN CIRCULATION; NORTH-ATLANTIC; SEDIMENT TRAP; FRAM STRAIT; RECONSTRUCTION
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
DOI etc.: 10.1016/j.marmicro.2012.06.006
ISSN: 0377-8398
Date Deposited: 29 Oct 2012 14:56
Last Modified: 21 Jun 2017 08:16
URI: http://eprints.uni-kiel.de/id/eprint/16583

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