Sea surface temperature records of core ZY2 from the central mud area in the South Yellow Sea during last 6200 years and related effect of the Yellow Sea Warm Current
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Sea surface temperature (SST) records in the South Yellow Sea during the last 6200 years are reconstructed by the unsaturation index of long-chain alkenones (U37K′) in sediment core ZY2 from the central mud area. The SST records varied between 14.1 and 16.5°C (15.6°C on average), with 3 phases: (1) A high SST phase at 6.2–5.9 cal ka BP; (2) A low and intensely fluctuating SST phase at 5.9–2.3 cal ka BP; and (3) A high and stable SST phase since 2.3 cal ka BP. Variation of the SST records is similar to intensity of the Kuroshio Current (KC), and corresponds well in time to global cold climate events. However, the amplitude of the SST response to cooling events was significantly different in different phases. The SST response to global cooling event was weak while the KC was strong; and the SST response was strong while the KC was weak. The difference in amplitude of the SST response is possibly caused by the modulation effect of the Yellow Sea Warm Current which acts as a shelf branch of the KC and a compensating current induced by the East Asia winter monsoon. The warm waters brought by the Yellow Sea Warm Current cushion the SST decrease induced by climate cooling, and both the Kuroshio and East Asian winter monsoon play important roles in the modulation mechanism. The SST records display a periodicity of 1482 years. The same period was found in the KC records, indicating that variation of the SST records in the central South Yellow Sea is strongly affected by KC intensity. The same period was also found in Greenland ice cores and North Atlantic and Arabian Sea sediment cores, showing a regional response of marine environmental variability in the East China Seas to that in the global oceans.
KeywordsSouth Yellow Sea U37K′ sea surface temperature Yellow Sea Warm Current Kuroshio Current climate change
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