毛乌素沙区1961-2016年降水特征

基于毛乌素沙区10个气象站1961-2016年观测资料，应用Mann-Kendall方法和t检验法对各气象站年降水量进行了突变检验，借助小波分析讨论了各气象站年降水量的周期特征，根据降水量等值线划分结果对整个研究区分区分析了年、季、月和日尺度上的降水变化特征，并在两个时段上分析了季节性降水的差异。结果表明：毛乌素沙区年降水量空间特征差异明显，东部亚区呈上升趋势，中西部亚区呈下降趋势，但变化趋势不显著且无突变发生；降水年内分配不均，干湿季分明，降水集中在5-9月，夏秋季降水占全年降水比重大，季、月和日尺度降水量存在梯度递减变化；年降水量的年际变化过程存在多重时间尺度的自相似结构；近26年的冬春季降水增加显著，但降水波动幅度小于前30年。

Characteristics of Precipitation in the Mu US Sandy Area during 1961-2016

Based on the precipitation data of 10 meteorological stations in the Mu Us Sandy Area from 1961 to 2016, the mutation detections of annual precipitation were tested by the Mann-Kendall method and t test, the periodic variation were discussed by the Morlet wavelet analysis method. Precipitation change characteristics on four time scales of year, season, month and day were analyzed according to precipitation isolines zone, and the differences of seasonal precipitation were analyzed in two time periods. Results showed that the spatial characteristics of annual precipitation in the Mu Us Sandy Area were obviously different, the eastern sub-region showed an upward trend while the central and western sub-regions showed a downward trend, however, the change trend was not significant and there were no mutations. Distribution of precipitation within a year is uneven, and the dry and wet seasons are distinct. The precipitation is mainly concentrated during the period of May-and September, the summer and autumn precipitation accounts for a dominant proportion of the annual precipitation. Moreover, the precipitation on four time scales of year, season, month and day have gradient decreasing change from east to west. A self-similar structure with multiple time scales existed in the process of inter-annual precipitation change. In the recent 26 years, the precipitation in winter and spring increased markedly, but the fluctuation range of precipitation was less than that in previous 30 years.