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Millennial-scale variability in the Indian monsoon and links to ocean circulation

<p> Millennial-scale variability in the Indian monsoon was temporally linked to changes in global ocean circulation during the last glacial period, as evidenced by planktic-benthic foraminiferal stable isotope and trace element results from an intermediate depth sediment core from the northwestern Bay of Bengal (Core NGHP-01-19B; 18&deg;58'N, 85&deg;39'E; 1,422 m). Paired planktic foraminiferal Mg/Ca and &delta;<sup>18</sup>O<sub>c</sub> of <i> G. ruber</i> constrain sea surface temperatures and isolate millennial-scale variations in the &delta;<sup>18</sup>O of surface waters (&delta;<sup> 18</sup>O<sub>sw</sub>) which resulted from changes in river runoff in the northwestern Bay. Concurrently with low &delta;<sup>18</sup>O<sub>sw</sub> events, benthic foraminiferal &delta;<sup>13</sup>C of <i>Cibicidoides </i> spp. decreased, suggesting an increased influence of an aged water mass at this intermediate depth site during the low salinity events. Benthic foraminiferal Cd/Ca of <i>H. elegans</i> supports the identification of this water mass as aged Glacial Antarctic Intermediate Water (GAAIW). Lagged correlation analysis (r= 0.41) indicates that changes in subsurface properties led changes in surface properties by an average of 380 years. The implication is that Southern Hemisphere climate exerted a controlling influence on the Indian monsoon during the last glacial period.</p>

Identiferoai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:1591709
Date23 July 2015
CreatorsDeLong, Kimberly
PublisherUniversity of New Hampshire
Source SetsProQuest.com
LanguageEnglish
Detected LanguageEnglish
Typethesis

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