中文摘要：

本文利用测站降水观测资料分析过去一百多年中国东部华北、长江流域以及华南夏季降水的年代际变化特征发现,尽管这三个地区的夏季降水具有不同的年代际转折时期,但是均同时在1910年代初期、1920年代初期、1940年代中期、1960年代中期、1970年代末期以及1990年代初期发生了跃变.近一百年间不同年代际时期东部夏季降水的分布型主要以南正北负或者南负北正的偶极型为主,并且无论是偶极型分布还是三极型分布,两个相邻年代际时期中国东部降水分布型发生完全反向变化的概率较高（60％）.此外,夏季的PDO、冬季的AO以及春季的北极海冰也同时在1920年代末期、1940年代中期、1970年代末期以及1990年代中期左右发生了跃变,这几次跃变时期与中国东部三个不同地区夏季降水发生跃变的时期一致,表现出近百年来太平洋年代振荡（PDO）、北极涛动（AO）以及北极海冰这三个因子对中国东部夏季降水年代际变化的协同作用.在年代际时间尺度上,夏季的PDO与华北夏季降水显著负相关.PDO的年代际变化能够在500 hPa位势高度场中激发出太平洋—日本（PJ）型年代际遥相关波列;同时在850hPa风场中激发出类似于影响华北夏季降水年代际变化的大气环流型,从而影响华北降水的年代际变化.冬半年的AO与长江流域夏季降水存在显著正相关关系.冬季到春季正位相的AO导致亚洲大陆南部处于湿冷状态,土壤湿度的记忆性可将这种状态延续到夏季.因此,夏季海陆热力对比减弱,东亚夏季风发生年代际减弱,相应地长江流域的降水年代际增多.春季北极海冰与华南夏季降水显著负相关,北极海冰的年代际异常能在500 hPa位势高度场中激发出与静止Rossby波异常传播相联系的欧亚—华南年代际遥相关波列,从而影响华南降水的年代际变化.

英文摘要：

In this paper, the interdecadal variations of rainfall over North China, the Yangtze River valley, and South China during the past 1 O0 years are examined using weather station data. The results show that the rainfall over these three regions underwent simultaneous shifts in the early 1910 s, the early 1920s, the middle t940 s, the middle 1960s, the late 1970 s, and the early 1990 s, although there are different interdecadal shifting periods. During the past 100 years the distribution patterns of summer rainfall over eastern China are primarily characterized by dipoles, such as ＂positive south and negative north＂ or ＂positive north and negative south＂ in different interdecadal periods. Furthermore, the probability of the totally reverse distribution patterns during two adjacent interdecadal periods is higher （60%） whether they are dipolar or tripolar. In addition, summer Pacific Decadal Oscillation （PDO）, winter Arctic Oscillation （AO）, and spring arctic sea ice also showed synchronous shifts around the late 1920s, the middle 1940s, the late 1970s, and the middle 1990s, consistent with the shifting periods of summer precipitation over three regions of eastern China, suggesting that PDO, AO, and arctic sea ice have played a synergetic role in the interdecadal variation of summer rainfall over eastern China during the past 100 years. At interdecadal time scales, PDO in summer is significantly negatively correlated with summer rainfall in North China. The interdecadal variability of PDO may generate interdecadal wave trains of Pacific-Japan （P J） interconnection pattern at 500-b.Pa geopotential height and atmospheric circulation in the 850-hPa wind field, which is similar to that affecting the interdecadal variation of summer rainfall over North China. Consequently, summer rainfall over North China showed interdecadal variation. The AO in wintertime is significantly positively correlated with summer rainfall over the Yangtze River valley. When AO enters its positive interdecadal phase from w