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降雨量和降雨的时间都是东亚季风活动的重要标志,绝大多数古气候研究只是用代表干/湿气候条件的替代指标重建降雨量以研究东亚季风系统的变化.而对降雨的时间即雨季变化的研究甚少.本文利用月分辨率的造礁珊瑚Sr/Ca和δ18O比值重建了南海北部雷州半岛地区中-晚全新世以来的季节性的雨季变化.与现代雨季主要发生在夏季-秋季(6-10月)不一样,~1500yrBP和~6800yrBP时期的雨季主要发生在秋季-冬季(8一12月),~2540yrBP和~5000yrBP时期的雨季主要发生在冬季-春季(分别为1-4月和12月-下一年3月).而~5900yrBP时期的雨季每一年发生的时间都不相同.雨季时间的变化表明雷州半岛中-晚全新世以来的气候条件经历了不同了温度-湿度配置变化,这种变化可能是由于东亚季风强度的变化和热带辐合带位置的变化引起的.需要开展进一步的尤其是气候变化的数值模拟方面的研究. “,”Precipitation amount and timing in East Asia are important factors of the East Asian monsoon. Many paleoclimate records that represent a proxy of wet or dry climatic conditions have been linked to changes in precipitation amount and are thus However, few studies have examined changes used to indicate changes in the East Asian monsoon system. in the timing of the rainy season. Here we report on records of the timing of the seasonal precipitation cycle during the mid-late Holocene, as derived from coupled high-resolution St/Ca and δ18O data of Porites corals from the northern South China Sea. These records indicate that the timing of the rainy season in this region has varied during the mid-late Holocene. The present-day rainy season generally occurs in surmner--autumn (June--October), which has also been recorded in Porites coral, whereas the rainy season at around 1500 yr and 6800 yr BP occurred in autumn--winter (August--December) , and the rainy season at around 2540 yr and 5000 yr BP occurred in winter--spring (January--April or December--March ). For the period around 5900 yr BP, the seasonal distribution of precipitation is variable from year to year. These shifts in the timing of the rainy season indicate changes in temperature-humidity patterns during the mid-late Holocene may reflect changes in the strength of East Asian monsoon and the location of the intertropical convergence zone.Further studies, particularly numerical modeling of climate in collaboration with meteorologists, are urgently required to address this uncertainty.