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Past 100 Ky surface salinity-gradient response in the eastern Arabian Sea to the summer monsoon variation recorded by delta super(18)O of G. sacculifer

DRS at CSIR-National Institute of Oceanography

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Title Past 100 Ky surface salinity-gradient response in the eastern Arabian Sea to the summer monsoon variation recorded by delta super(18)O of G. sacculifer
 
Creator Chodankar, A.R.
Banakar, V.K.
Oba, T.
 
Subject palaeo studies
coastal currents
salinity gradients
oxygen isotopes
surface circulation
sea level changes
surface temperature
summer
monsoons
forminifera
plankton
 
Description Northward flowing coastal currents along the western margin of India during winter-spring advect low-salinity Bay of Bengal water in to the Eastern Arabian Sea producing a distinct low-salinity tongue, the strength of which is largely governed by the freshwater flux to the bay during summer monsoons. Utilizing the sedimentary records of delta sup(18) O sub(G. sacculifer), the past salinity-gradient within that low-salinity tongue is reconstructed, which serves as a proxy for the variation in freshwater flux to the Bay of Bengal and hence summer monsoon intensity. The north-south contrast in the sea level corrected (residual)-delta sup(18) O sub(G. sacculifer) can be interpreted as a measure of surface salinity-contrast between those two locations because the modern sea surface temperature and its past variation in the study region is nearly uniform. The core-top residual- delta sup(18) O sub(G. sacculifer) contrast of 0.45 ppt between the two cores is assumed to reflect the modern surface salinity difference of 1 psu and serves as a calibration for past variations. The residual delta sup(18) O sub(G. sacculifer) contrast varies between approx. 0.2 ppt at approx. 75 ky B.P. (i.e., late-Marine Isotope Stage 5) and approx. 0.7 ppt at approx. 20 ky B.P. (i.e., Last Glacial Maximum), suggesting that the overall salinity difference between the northern- and southern-end of the low-salinity tongue has varied between approx. 0.6 and approx. 1.6 psu. Considerably reduced difference during the former period than the modern suggests substantially intensified and northward-extended low-salinity tongue due to intense summer monsoons than today. On the other hand, larger difference (approx. 1.6 psu) during the latter period indicates that the low-salinity tongue was significantly weakened or withdrawn due to weaker summer monsoons. Thus, the salinity-gradient in the eastern Arabian Sea low-salinity tongue can be used to understand the past variations in the Indian summer monsoons
 
Date 2008-02-22T05:31:31Z
2008-02-22T05:31:31Z
2005
 
Type Journal Article
 
Identifier Global and planetary change, Vol.47; 135-142p.
http://drs.nio.org/drs/handle/2264/986
 
Language en
 
Rights Copyright [2005]. It is tried to respect the rights of the copyright holders to the best of the knowledge. If it is brought to our notice by copyright holder that the rights are voilated then the item would be withdrawn.
 
Publisher Elsevier