Abstract:

The precipitation data observed by 160 meteorological stations in the eastern China (the east of 110°E) in more than 100
years were used to study the changes of precipitation and the distribution of extremely more or less rainfall years in the eastern China in-
cluding north China，Yangtze River Valley and south China region． The method of Z index was used to transform drought and flood area
and study the changes of the dry or waterlogged area and the distribution of extremely dry or waterlogged years in eastern China in more
than 100 years． Results show that the extremely more rainfall years in more than 100 years distributed evenly in eastern China and the
interval was about 20 to 40 years，and the extremely less rainfall years decreased． There was an oscillating period about 40 －50 years
for the precipitation variation． The precipitation increased significantly in summer，and decreased obviously in autumn． The trend of an-
nual rainfall along the Yangtze River Basin was consistent with the annual precipitation variation in the east China，which illustrated the
Yangtze River Basin precipitation contributed significantly to the eastern China，and the secondary one was south China rainfall． There
was no obvious increasing or decreasing trend for drought or flood area in the east China in more than 100 years，but there was obvious
interannual and interdecadal oscillation． The maximum drought area mainly concentrated before the 1930s in east China，and after 1969
its change trend wasn＇t obvious． The extremely drought years in the northeast and north China mostly appeared before 1940，and ex-
tremely drought years in the Yangtze River Basin and south China distributed evenly．

Key words:  the twentieth century, east China, precipitation, extreme drought and flood, variations

摘要：

根据我国东部地区(110°E 以东) 160 个观测站 100 多 a 的降水资料对我国东部地区包括华北地区、长江流域和华南地区等 100 多 a 的降水变化趋势和降水极端偏多和极端偏少年份的分布进行了分析;并通过计算 Z 指数，实现旱涝面积转化，分析我国东部 100 多 a 来的旱、涝范围变化和极端旱、涝年份的分布。结果表明:我国东部地区 100 多 a 的降水极端偏多年份随时间分布比较均匀，其间隔在 20 ～40 a 间。降水极端偏少年份在减少。降水量的变化存在着大约 40 ～ 50 a 的震荡周期。夏季降水增加明显，秋季降水下降明显。长江流域的年降水量和我国东部年降水量趋势保持较好的一致性，说明长江流域的降水对我国东部降水的贡献显著，华南区域的降水起次要作用。我国东部近100 a 来雨涝范围和干旱范围都没有表现出明显的增、减趋势，但存在着明显的年际和年代际振动。我国东部干旱覆盖面积最大的时间主要集中在 1930 年代以前，1969 年以后变化趋势不明显。东北和华北极端干旱年份大都出现在 1940 年以前，长江流域和华南的极端干旱年份则随时间分布比较均匀。

关键词: 20 世纪, 中国东部, 降水, 极端旱涝, 变化规律