1756 / 2019-08-29 07:00:57

Early-Holocene paleo-tropical cyclone activities inferred from a sedimentary sequence in South Yellow Sea, East Asia

1、第四纪地质与全球变化 > 专题5：晚更新世—全新世东亚环境演变记录

Tropical cyclones play a critical role in global climate changes; however, their long-term variations in the past have not been documented comprehensively. In this study, we collected a sedimentary sequence from the South Yellow Sea to extract possible information on tropical-cyclone influences during depositional processes. By integrating radiocarbon dating and sediment grain-size analysis, we found that the studied core was deposited during the Holocene and sedimentary dynamics was relatively stable and low, with median grain sizes of 5.3~8.7 μm. These results show that coarse particles in the sediments would be related to high-dynamic sedimentary events. After comparing the grain-size characteristics of the South Yellow Sea with those of the Bohai Sea and the East China Sea, we derived a paleo-tropical cyclone variation from the coarse particles of the early Holocene and observed a considerable fluctuation. Based on this derived paleo-tropical cyclone variation, we identified several intervals with low tropical cyclone intensities and report good consistencies of the paleo-tropical cyclone variation with the changes in solar activity, monsoonal intensity, and El Niño–Southern Oscillation. Thus, this study suggests that tropical cyclones may have significantly contributed to Asian monsoon variations on centennial timescales. Furthermore, the mechanism is supposed as follows, solar maxima may have strengthened the Walker circulation over the tropical Pacific and subsequently intensified both tropical cyclones and Asian monsoon in the Northwest Pacific during the early Holocene.