HR: 11:05h
AN: PP12B-04    [Abstracts]
TI: Gulf Stream Density Structure and Transport during the Last Millennium
AU: * Lund, D C
EM: dlund@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole, MA 02543 United States
AU: Lynch-Stieglitz, J
EM: jean@eas.gatech.edu
AF: Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA 30332 United States
AU: Curry, W B
EM: wcurry@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole, MA 02543 United States
AB: The Gulf Stream is a key component of the global oceanic circulation, acting as the northward surface compensation for meridional overturning as well as the western boundary of the North Atlantic subtropical gyre. Using a suite of 13 well-dated, high-resolution cores from the Straits of Florida, we reconstructed the density structure of the Florida Current (the portion of the Gulf Stream confined to the Straits) using benthic and planktonic foraminiferal δ¹⁸O. We found that the average cross-current density gradient and vertical current shear varied by ~10% during last millennium. Assuming a constant level of no motion at 850 m water depth, we estimate that Florida Current transport was 3 ± 1 Sv lower during the Little Ice Age (1200 - 1850 A. D.) than today and ~1000 A. D. The timing of reduced flow is consistent with anomalously cold conditions inferred from several paleoclimate archives, implicating Atlantic oceanic heat transport in centennial-scale climate variability of the last millennium. Lower volume transport occurred primarily in the 100-500 m depth range of the Florida Current, water which today originates in the wind-driven subtropical gyre. This suggests that low flow during the Little Ice Age was largely a function of weaker winds in the mid- to low-latitude North Atlantic.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1620 Climate dynamics (0429, 3309)
DE: 4512 Currents
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005