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PALEOPRODUCTIVITY VARIATIONS IN THE EQUATORIAL ARABIAN SEA: IMPLICATIONS FOR EAST AFRICAN AND INDIAN SUMMER RAINFALLS AND THE EL NIO FREQUENCY
Abstract
We analyzed a sediment core from the equatorial Arabian Sea, chronologically constrained by accurate accelerator
mass spectrometry (AMS) radiocarbon dates on selected planktonic foraminiferal species, for paleoproductivity variations
corresponding to the variations in the Indian Ocean Equatorial Westerlies (IEW). The IEW in turn are positively
correlated to the Southern Oscillation Index (SOI), which is a measure of El Nio, Southwest monsoon (SWM), and east African
rainfall (EAR). The productivity data show that Indian and east African rainfalls declined from 35,000 calendar yr BP up
to the last glacial maximum (LGM), with the maximum El Nio frequency during the last glacial period. From ~14,500 to
~2000 calendar yr BP (i.e. core top), we find strengthening SWM and EAR along with declining El Nio frequency.
mass spectrometry (AMS) radiocarbon dates on selected planktonic foraminiferal species, for paleoproductivity variations
corresponding to the variations in the Indian Ocean Equatorial Westerlies (IEW). The IEW in turn are positively
correlated to the Southern Oscillation Index (SOI), which is a measure of El Nio, Southwest monsoon (SWM), and east African
rainfall (EAR). The productivity data show that Indian and east African rainfalls declined from 35,000 calendar yr BP up
to the last glacial maximum (LGM), with the maximum El Nio frequency during the last glacial period. From ~14,500 to
~2000 calendar yr BP (i.e. core top), we find strengthening SWM and EAR along with declining El Nio frequency.