陕北荒漠区降水量演变规律研究

为了解陕北荒漠区降水演变规律,分析了榆林气象站1951-2013年降水量的基本统计特征,采用R/S法分析了序列的持续性,Kendall秩次相关检验分析趋势性,功率谱分析法分析周期,Mann-Kendall法和累积距平法相结合分析突变。结果显示:年降水量呈现递减趋势并将持续,周期为2.66年,显著突变发生在20世纪60年代末。年最大日降水量呈现不显著递增趋势,且发生在8月比例最大,无显著突变发生。大于5 mm和大于10 mm的日降水量累计值均呈现不显著递减趋势,周期均为3年,且显著突变均发生在20世纪70年代初。1、3、5、6、9月的月降水量呈现微弱递增趋势,其他月份均表现为微弱递减趋势;对汛期7-10月降水量的突变分析显示,汛期4个月降水均无显著突变。榆林站降水总体呈现递减趋势。

Evolution law of precipitation in desert area of northern Shaanxi

In order to understand the evolution law of precipitation in the desert area of northern Shaanxi, the paper analyzed the basic statistical characteristics of precipitation data at the weather station of Yulin from 1951 to 2013.It used R/S analysis method to analyze the persistence sequence, Kendall rank correlation test to analyzed the trend, the method of power spectrum to analyze the period,and combined the Mann-Kendall and accumulative departure curve method to analyze the mutation.The result showed that the annual precipitation presents the decreasing trend and will continue to decrease and the period is 2.66 years, the notable mutation occurs in end of 1960s.The annual maximum daily precipitation presents an insignificant increasing trend,and the proportion occurred in August is the largest, there is no significant mutation.The cumulative daily precipitation of more than 5mm and less than 10mm present insignificant decreasing trend, the period is 3 years and the significant mutation occurs in early 1970s.The monthly precipitations in January, March, May, June and September present insignificant increasing trend. The precipitations in other months present an insignificant decreasing trend.The mutation analysis of precipitation in flood season from July to October showed that there are no significant mutations in the four months. The precipitation in Yulin station presents a decreasing trend on the whole.