中文摘要：

对中国北方243个站点1958-2009年逐月降水资料，采用小波分析和奇异谱分析（SSA）方法，在分4区基础上，对北方不同地区降水的周期和趋势进行分析，并进行比较。结果表明，西北地区（青海区、干旱区）降水的趋势性比北方中、东部区的明显。北方中、东部区在20世纪50年代末到60年代相对多雨，而青海区、干旱区在20世纪50年代末到70年代末或80年代中相对少雨。在20世纪80年代，北方中部区降水由偏多转为偏少，而其余3个区域（北方东部区、青海区、干旱区）的降水由偏少转为偏多，发生和持续时间各不相同。近几年，北方东部区、北方中部区、青海区的降水增加，而干旱区降水下降。北方东部区、中部区、干旱区存在10年以上的长周期，北方东部区为准22年，北方中部区为准15年，干旱区为准11年，这种长周期在20世纪80年代之后变得规则且稳定。北方降水普遍存在准2-3年周期和准5年周期，其振幅有明显的年际、年代际变化，具有一定的周期性。

英文摘要：

Based on division, precipitation cycle and trend in different areas of Northern China （NC） are analyzed and compared by using wavelet analysis and singular spectrum analysis based on the monthly precipitation da- ta of 243 stations in the northern part of China during 1958-2009. The study results show that the precipitation in Northwest China （ Qinghai Area and Arid Area） has stronger tendency than that in the Eastern NC and Middle NC. From the late 1950＇ s to 1960＇ s the precipitation in Eastern NC and Middle NC was on high side, while it was on low side in Qinghai and Arid Area at that time. During the 1980＇ s, the precipitation in Middle NC turned fromhigh side to low side, while it turned reversely in the other three areas. The turning point and the lasting time were different in different areas. In recent several years, the precipitation has increased in Eastern NC, Middle NC and Qinghai area, and decreased in Arid Area. Except for Qinghai area, precipitation in Northern China has longer pe- riod than 10 years--22 a in Eastern NC, 15 a in Middle NC and 11 a in Arid Area--that has became stable and significant since the 1980＇ s. Northern China＇ s precipitation, in common, has a period of 2 -3 a and 5 a. The os- cillation amplitude has obvious inter-annual and inter-decadal variability, which is quasi-periodic.