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Gulf stream temperature, salinity and transport during the last millennium

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dc.contributor.advisor William B. Curry. en_US Lund, David Charles en_US
dc.contributor.other Woods Hole Oceanographic Institution. en_US 2006-11-07T13:02:31Z 2006-11-07T13:02:31Z 2005 en_US 2006 en_US
dc.description Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), February 2006. en_US
dc.description Includes bibliographical references. en_US
dc.description.abstract Benthic and planktonic foraminiferal [delta]18O ([delta 18Oc) from a suite of well-dated, high-resolution cores spanning the depth and width of the Straits of Florida reveal significant changes in Gulf Stream cross-current density gradient during the last millennium. These data imply that Gulf Stream transport during the Little Ice Age (LIA: 1200-1850 A.D.) was 2-3 Sv lower 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 pattern of flow anomalies with depth suggests reduced LIA transport was due to weaker subtropical gyre wind stress curl. The oxygen isotopic composition of Florida Current surface water ([delta]18Ow) near Dry Tortugas increased 0.4%0/ 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]18Ow increased by 0.3%o during the last 200 years. Although a portion (-O. 1%o) of this shift may be an artifact of anthropogenically-driven changes in surface water [Epsilon]CO2, the remaining [delta]18Ow signal implies a 0.4 to 1 psu increase in salinity after 200 yr BP. en_US
dc.description.abstract (cont.) The simplest explanation of the [delta]18Ow, data is southward migration of the Atlantic Hadley circulation during the LIA. Scaling of the [delta]18Ow records to salinity using the modern low-latitude 180,w-S slope produces an unrealistic reversal in the salinity gradient between the two sites. Only if [delta]18Ow is scaled to salinity using a high-latitude [delta]18Ow-S slope can the records be reconciled. Changes in atmospheric 14C paralleled shifts in Dry Tortugas [delta]18Ow, suggesting that variable solar irradiance paced centennial-scale Hadley cell migration and changes in Florida Current salinity during the last millennium. en_US
dc.description.statementofresponsibility by David C. Lund. en_US
dc.format.extent 256 p. en_US
dc.format.extent 27095353 bytes
dc.format.extent 27094557 bytes
dc.format.mimetype application/pdf
dc.format.mimetype application/pdf
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.subject Joint Program in Oceanography. en_US
dc.subject Earth, Atmospheric, and Planetary Sciences. en_US
dc.subject Woods Hole Oceanographic Institution. en_US
dc.subject.lcsh Ocean-atmosphere interaction en_US
dc.subject.lcsh Paleoclimatology en_US
dc.title Gulf stream temperature, salinity and transport during the last millennium en_US
dc.type Thesis en_US Ph.D. en_US
dc.contributor.department Joint Program in Oceanography. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences. en_US
dc.contributor.department Woods Hole Oceanographic Institution. en_US
dc.identifier.oclc 71196904 en_US

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