A Paleoceanographic Reconstruction Of North Atlantic Ocean Circulation
Date
2022-05
Authors
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Publisher
University of Delaware
Abstract
This project applies Globorotalia truncatulinoides coiling ratios as a proxy for
changes in upper ocean hydrography and gyre circulation in the northeastern region of
the North Atlantic subtropical gyre over the past 140 thousand years, covering both
glacial and interglacial intervals. We used sediment cores from Integrated Ocean
Drilling Program Site U1313 to assess the changes in coiling variety. In the modern
ocean, this gyre region displays a deep permanent thermocline, favoring the left
coiling (sinistral) form. At Site U1313 there are variations in percent sinistral during
the warm interglacial interval Marine Isotope Stage 5 (MIS 5) with an increase in the
dextral form during the colder substages MIS 5a and c. Previously published sites
underneath the western boundary current (Site KNR140-37 PC) and in the center of
the gyre (Integrated Ocean Drilling Program Site 1063) show that the percent sinistral
stays high throughout interglacial intervals, including MIS 5, and the right coiling
(dextral) form dominates during glacial periods. This study’s results are different than
previously published data, as there are exceptions to the glacial versus interglacial
trend during MIS 5, which suggests a change in gyre circulation and intensity not
previously reconstructed. Further comparison to the previously published sites and
analysis of additional subpolar sites will help interpret the hydrographic changes
occurring in the North Atlantic subtropical gyre.
Description
Keywords
North Atlantic Ocean, Ocean hydrography, Gyre circulation