中文摘要：

利用1961-2008年新疆49个气象观测站逐月降水量计算相应标准化降水指数（SP I）,利用RPCA模态分析的方法研究新疆极端干旱的气候特征.结果表明：1961-2008年新疆极端干旱面积率总体处于减小趋势;20世纪80年代以前极端干旱面积率较大,基本在20%以上;80年代后在10%左右;2000年后极端干旱面积率有增加的趋势;M-K突变检验表明,极端干旱突变出现在20世纪70年代中期.新疆北部是极端干旱发生频率最高的区域,利用主成分旋转法可将新疆极端干旱分为3个区域：北疆区（代表站为石河子观测站）、南疆区（代表站为柯坪观测站）和东疆区（代表站为七角井观测站）.依据极端干旱年的定义,1961-2008年新疆极端干旱年份分别是1962-1965,1967-1968,1973-1979,1982,1984-1985,1991,1995和1997年,其中强极端干旱年分别是1962,1974-1975和1997年,相应年份极端干旱的站数远远超过该时段平均值.

英文摘要：

With monthly precipitation data from 49 meteorological stations in Xinjiang during 1961-2008, the corresponding SP I were calculated and then the climatic characteristics of extreme drought in Xinjiang were studied by using the RPCA modal analysis methods. The results show that in general, from 1961 to 2008, the ratio of extreme drought area in Xinjiang showed a decreasing trend. Before 1980 s, the extreme drought area was larger, almost above 20%. After 1980 s, it was about 10%; From 2000, the extreme drought area showed an increasing trend; M-K test showed that there was an abrupt change of the extreme drought in mid-1970 s.The northern part of Xinjiang was the region with the highest occurring frequency of extreme drought, and the extreme drought of Xinjiang could be separated into three regions by using the principal component rotating method： North of Xinjiang（the representative station is Shihezi）, South of Xinjiang（the representative station is Keping） and East of Xinjiang（the representative station is Qijiaojing）. According to the definition of extreme drought, the extreme drought years in Xinjiang during 1961-2008 were 1962-1965, 1967-1968, 1973-1979,1982, 1984-1985, 1991, 1995 and 1997, and the strong extreme drought years were 1962, 1974-1975 and 1997,with the extreme drought stations in the corresponding years far exceeding the average numbers of that period.