中文摘要：

利用西北干旱区1961—2007年77个观测站的逐日降水资料序列,将西北干旱区分为5个主要气候区,分析了全球变暖背景下西北干旱区雨季的降水时空变化特征,并预测降水的未来变化趋势。结果表明：西北干旱区降水存在显著的年际和年代际变化,其西部降水量呈显著上升趋势,尤其在新疆北部与伊犁河谷地区。降水具有5～6年或2～3年的年际周期与8～11年的年代际周期,但河西走廊地区例外。干旱区降水转型时期的空间差异显著,最早在1980年代初期从南疆开始,1980年代中期新疆北部降水出现异常偏多,伊犁河谷和河西走廊地区降水突变期则出现在1990年代初,但变化趋势相反;阿拉善高原地区降水没有明显的突变时间。由周期外推方法得到,在未来一个年代际周期中,西北干旱区的西部降水将以偏少的气候特征为主,直到2015年前后才会再次回到偏多的周期中来;阿拉善高原地区在未来8～11年中有可能向着降水增加的趋势发展。

英文摘要：

The spatiotemporal characteristics of rainy season precipitation for the five climatic subareas of Northwest China arid region（NCAR） under the background of global warming were investigated by using the daily precipitation data at 77 representative stations from 1961 to 2007,and future trends of the precipitation in the next decades were projected as well.The results are summarized as follows.1） The precipitation in the NCAR presented significant interannual and interdecadal variabilities.The rainfall in western NCAR exhibited obvious increasing trends,especially in northern Xinjiang and the Yili River valley.There were generally two interannual periodic oscillations of five-to six-year and two-to three-year and one interdecadal cycle of eight-to eleven-year in rainy season precipitation time series in most areas of the NCAR,but in the Hexi Corridor,the thirteen-to fourteen-year long cycle dominated the interdecadal variability.2） The abrupt change dates of precipitation in the five subareas were distinctively different from each other.The abrupt change from less to more than normal occurred in southern Xinjiang in the early 1980s,and then reached northern Xinjiang in the middle 1980s,the opposite trend abrupt change occurred in the Yili River valley and the Hexi Corridor region in the early 1990s,however no remarkable trend change was detected in the Alxa Plateau.3） In the next interdecadal cycle,the precipitation will sustain the less than normal regime until the year of 2015 in western NCAR,afterwards return to the more than normal regime;while the precipitation may become more than normal in the next eight to eleven years in the Alxa Plateau.