季风区边缘近500年的降水变化特征

基于武都万象洞高分辨率石笋δ¹⁸O和高精度²³⁰Th定年数据,结合利用周边地区史料恢复的旱涝指数序列,重建季风区边缘近500 a以来降水变化。结果显示:在年际至百年时间尺度上,万象洞石笋δ¹⁸O变化指示亚洲季风带来的降水量信息。季风区边缘降水变化可分减弱期(1470~1700 A.D.)、平稳期(1701~1875 A.D.)和增强期(1876~2003 A.D.)三个气候段,其间季风降水的强弱变化响应史料记载的极端旱涝事件。在小冰期向20世纪暖期转换过程中,本区呈现阶梯式过渡降水模式,这是一种较大空间尺度上气候特征,在年代际至百年时间尺度上与北半球温度、中国温度变化具有同步性。

A Comprehensive Study on Precipitation Change Over Monsoon Marginal Areas During Last Five Centuries

Based on high-precision ²³⁰Th dates and high-resolution oxygen isotope records of a stalagmite collected from Wanxiang Cave,Wudu,together with the references of Chinese historical documents from Wudu and the neighboring areas,the variation of monsoonal precipitation in the modern Asian monsoon marginal zone over the past 500 years was reconstructed.This study indicated that the speleothem δ¹⁸O is a good proxy for the Asian monsoon strength and associated precipitation on inter-annual to centennial timescale.Variation of the monsoonal precipitation during the past 500 years can be divided into three stages,decreasing from 1470 A.D.to 1700 A.D.,stable between 1701 A.D.and 1875 A.D.,and increasing thereafter.This variation is quite similar to that of the Drought/Flooding index archived from Chinese historical documents.Monsoonal precipitation shows stepwise pattern in the monsoonal marginal region of China during the transition from the Little Ice Age to the Current Warm Period.The variation of stepwise precipitation suggested that the monsoonal precipitation over the monsoon marginal zone in large-spatial-scale is consistent,and this variation and the Northern Hemisphere temperature,Chinese temperature varied synchronously on interdecadal to centennial timescale.