1868年长江中下游“二度梅”的雨带推移过程

The Rain-Band Shift of the Second Plum Rain Over the Yangtze River Valley during 1868

本文尝试使用高分辨率的清代日记资料,复原1868年长江中下游各地夏季降水情况,辨析出当年梅雨季节各地的降水时间和主要降水过程,发现该年发生了"二度梅"现象。该年入梅较早,6月8日全流域降水就已经开始,且14日以后雨带有北抬趋势,但很快南撤出长江流域,引起降水中断。直至7月5日开始,雨带又重新占据长江南岸,带来第二段梅雨。"二度梅"的发生可能与副高持续南撤有关。

By using High-Resolution weather information from diaries of Qing dynasty,the paper reconstructs the spatial and temporal distribution of summer precipitation over the Yangtze River Valley in 1868 and discriminates the accurate date of rainfall of several stations.The result shows that secondary plum rain happened in 1868.The plum rain started at June 8,and the rain-band had moved Northern of the Yangtze River valley for a few days after June 18.Then the rain-band retreated back and led to breakup of the plum rain.The rain-band reappeared on July 5 and located southern bank of Yangtze River,and it brought the secondary plum rain.The movements of rain-band is probably caused by the retreat of Pacific subtropical high（WPSH）.