山东主雨季突变特征及成因

Mutations Characteristics and Its Causes of the Main Rainy Season in Shandong Province

采用山东省111个地面测站45年（1965-2009年）逐日降水量资料，分析了山东主雨季的气候特征，特别是降水量的突变性。经统计检验确认，5～10月候（日）降水量（以下简称降水）序列存在3次突增或骤减的显著突变，主雨季定义在第1次突变至第3次突变之间，即36～49侯，历时14侯。第2次突变发生在8月中旬，是主雨季内一个短时降水减少过程，与副高的短暂南撤有关。突变是在降水的年循环和季节变化背景下，由月内振荡对季节内振荡的调制中发生的。主雨季的进程与副高和西风带系统相对位置的变动紧密相关，3次突变的环流特征各不相同，每一次突变都显示出特定的环流结构，山东主雨季起讫的降水突变是由不同尺度大气环流相互调整的结果。

Using daily precipitation data from 111 weather stations during 1965-2009, the climate characteristics of main rainy season are analyzed in Shandong province. Confirmed by the statistical test, there are three rainfall mutations from May to October, the main rainy season stands between the first and the third mutation, that is, its duration period is 14 pentads from the 36th to the 49th pentad. The second mu- tation occurred in mid-August, which is related to the Southern briefly withdraw of the West Pacific subtropical high. Mutation events occur in the background of annual cycle and seasonal variation of precipita tion, through which the intra-monthly oscillation modulates the intra-seasonal oscillation. Process of the rainy season is closely related to the subtropical high and the westerlies system changes. Circulation characteristics of three mutation events are different, and each mutation has an identified circulation structure. Mutations of precipitation of the main rainy season in Shandong are determined by the atmospheric circulation adjustment.