第七届青年地学论坛

We present a reconstruction of summer sea-surface salinity (SSS) over the past 6800 years based on a diatom record from piston core MD05-2908, located in the southern Okinawa Trough (OT), East China Sea. The modern summer SSS is primarily controlled by river runoff from Taiwan, South China, linking to summer precipitation in the area which is strongly affected by the East Asian summer monsoon (EASM). The reconstruction presented in this study shows that the summer SSS increased gradually since 6800 cal. yr BP, indicating reduced precipitation in Taiwan from the mid Holocene to the late Holocene, which is comparable to the precipitation records in southeastern (SE) China. The long-term summer SSS trend closely followed the trend of the weakening EASM and solar insolation since the mid Holocene, suggesting that summer SSS in the southern OT had an obviously negative response to the variability of the EASM. On the other hand, summer SSS in the northern OT, which was strongly influenced by the Changjiang River discharge, shows a slight increase in summer precipitation in central eastern China over the past 6800 cal. yr BP. This apparent inconsistence can be interpreted as a lengthening of the Meiyu rains and shortened midsummer stage from the mid Holocene to the late Holocene. The results above are supported by model simulations, which further reveals the role of the westerlies in communicating the North Atlantic influence to the East Asian climate.

sea surface salinity,East Asian summer monsson,Okinawa Trough