Link between western Arabian sea surface temperature and summer monsoon strength and high-latitude abrupt climate events
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Sea surface temperature (SST) is modulated by the summer monsoon winds and the associated upwelling in the Arabian Sea. Here, I report the changes of summer and winter SST's in the western Arabian Sea reconstructed for the last 22 ka using Artificial Neural Networks (ANN's) based on quantitative analyses of planktic foraminifera. High seasonal SST contrast between winter and summer during the last glacial period indicates weak upwelling and strong cold northeasterly winds. Minimum seasonal SST contrast during the Holocene reflects strong upwelling. Contrast between summer and winter SST's documented here is in agreement with the other upwelling proxies recorded in the Arabian Sea sediments over the time span covered in the present study. This suggests that seasonal SST is a potential proxy to quantify the upwelling and the associated monsoon strength in the Arabian Sea. During an intense phase of monsoon in the Early Holocene a drastic reduction of annual summer and winter SST's is documented around 8.2 cal ka, which coincides with a decline of the monsoon upwelling strength. A similar cooling event around 8.2 cal ka was recognized in the north Atlantic as well as in the tropics. This suggests a link between high-latitude climate on the one hand and monsoon upwelling strength in the Arabian Sea and tropical climate changes on the other.
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