不同时间尺度下的贵州省修文县干旱特征分析

Analysis of Characteristics of Droughts under Different Time Scales in Xiuwen County of Guizhou

利用修文县气象站1963—2011年连续49 a的逐月降水资料,以降水距平百分率作为干旱等级评价指标,从年尺度、季尺度和月尺度分别对修文县的干旱特征进行了分析。结果表明,修文县的年度干旱存现长短周期交替出现的规律,且在长、短周期变换的年份出现严重干旱的概率较大;春、夏、秋和冬季出现干旱的概率分别是24.49%、20.41%、20.41%和18.37%,春旱出现概率最高。全年每个月都可能发生不同程度干旱,其中11月发生干旱的概率最大,为11.92%;年降水量越小的年份,季尺度和月尺度严重干旱概率越大。

The characteristics of drought in Xiuwen county are analyzed from the annual,seasonal and monthly scales,by using the monthly precipitation data from 1963 to 2011 in Xiuwen county.The characteristics of different grade droughts are analyzed with precipitation anomaly percentage as drought grade evaluation index.The results show that the annual scale drought in Xiuwen county is long period and short period alternating,and there is a high probability of serious drought in the years of long and short cycle transformation.The occurrence frequency of spring,summer,autumn,winter drought are 24.49%,20.41%,20.41%and 18.37%,of which the spring drought is the highest.There may be different degrees of droughts every month throughout the year,the probability of drought in November was the largest,which is 11.92%.The probability of severe drought on the seasonal scale and monthly scale is greater in the year with smaller annual precipitation.