Abstract: Using constructed and observational data of seasonal precipitation in Eastern China (east to 110°E) over 1880-2004, major characters of spatial distribution of precipitation in each season are studied with EOF analysis. Two primary patterns of spatial distribution are found. While precipitation in winter, spring and autumn belong to the first pattern, summer is of the second one. Furthermore, combined with the constructed data of 1880?1950 and observational data of 1951-2004 on 500?hPa geopotential height, the impact of circulation on seasonal precipitation is studied. The results show that the spatial distribution of abnormally seasonal precipitation usually has a close connection with high?level circulations, and the relationship of the two is stable in the past hundred years or more. Finally, research on the periodic variation of spatial structure of seasonal precipitation reflects that every season has interannual and interdecadal variability. The outcome of spectral analysis and wavelets shows that the periods of 2-4 a, 5-8 a, 15 a, 20-25 a and 60 a are the leading cycles of seasonal precipitation in Eastern China.

Key words: seasonal precipitation, spatial distribution, interannual variation, interdecadal variation

摘要： 利用观测资料和史料所重建的中国东部（110°E以东）71站1880?2004年的四季降水量序列，通过EOF分析得到了各个季节降水量空间分布的主要形态，并且按其特点分为两类，冬春秋季为一类，夏季为一类。利用重建的1880?1950年和观测的1951?2004年的500 hPa高度场资料，分析了大气环流对各季降水异常的影响。结果表明，各季的降水异常分布形态与高空环流形势有很好的对应关系，并且近百年来这种对应关系比较稳定。最后研究了各季降水量空间结构的周期变化特征，结果显示各个季节降水量空间分布形态都存在高频的年际变化和低频的年代际变化。功率谱和子波分析表明，高频集中于2～4年、5～8年，而低频则集中在15年、20～25年、60年，共同代表了中国季节降水异常变化的主要周期。

关键词: 季节降水, 空间分布, 年际变化, 年代际变化