Gulf Stream Temperature, Salinity and Transport During the Last Millennium

Benthic and planktonic foraminiferal delta (exp 18) oxygen (delta(exp 18)Oxygen(sub c) from a suite of well-dated, high-resolution cores spanning the depth and width of the Straits of Florida indicate Gulf Stream vertical current shear was anomalously low during the Little Ice Age (LIA: 1200-1850 A....

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Bibliographic Details
Main Author: Lund, David C.
Other Authors: MASSACHUSETTS INST OF TECH CAMBRIDGE JOINT PROGRAM IN APPLIED OCEAN SCIENCE AND ENGINEERING
Format: Text
Language:English
Published: 2006
Subjects:
Geology
Geochemistry and Mineralogy
Physical and Dynamic Oceanography
*TEMPERATURE
*SALINITY
*GULF STREAM
*PALEOCLIMATOLOGY
HEAT TRANSFER
THESES
HIGH RESOLUTION
MOISTURE CONTENT
TIME
FLORIDA
STRAITS
NORTH ATLANTIC OCEAN
VARIABLES
CHEMICAL COMPOSITION
OXYGEN
SURFACE WATERS
ISOTOPES
SOLAR RADIATION
LIA(LITTLE ICE AGE: 1200-1850 A.D.)
North Atlantic
Online Access:http://www.dtic.mil/docs/citations/ADA454903
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA454903
Description
Summary:Benthic and planktonic foraminiferal delta (exp 18) oxygen (delta(exp 18)Oxygen(sub c) from a suite of well-dated, high-resolution cores spanning the depth and width of the Straits of Florida indicate Gulf Stream vertical current shear was anomalously low during the Little Ice Age (LIA: 1200-1850 A.D.). Assuming a constant level of no motion, the foraminiferal data imply transport was 2-3 Sv lower during the LIA than today. The timing of reduced flow is consistent with cold conditions in Northern Hemisphere paleoclimate archives, implicating Gulf Stream heat transport in centennial-scale climate variability of the last 1,000 years. The oxygen isotopic composition of Florida Current surface water ((delta(exp 18)Oxygen (sub w) near Dry Tortugas increased 0.4%o during the course of the Little Ice Age (LIA: -1200-1850 A.D.), equivalent to a salinity increase of 0.8-1.5 psu. On the Great Bahama Bank, where surface waters are influenced by the North Atlantic subtropical gyre, delta(exp 18) oxygen(sub w) increased by 0.3%o during the last 200 years, a 0.4 to 1 psu increase in salinity. The simplest explanation of the delta(exp 18) Oxygen(sub w) data is southward migration of the Atlantic Hadley circulation during the LIA. Changes in atmospheric 14C paralleled shifts in Dry Tortugas delta(exp 18) Oxygen(sub w), suggesting that variable solar irradiance paced centennial-scale Hadley cell migration and changes in Florida Current salinity. The original document contains color images.

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