利用1960-2010年中国1840个台站年降水量数据,采用经验正交函数(EOF)和旋转经验正交函数分解方法(REOF)对降水进行分区,并对各区降水的变化特征进行了研究。结果表明：基于多站点资料结合REOF方法实现的降水分区与中国降水实际区域分异特征比较符合,并与中国气候区划相一致。中国各区降水变化特征分析表明,东部各区降水在20世纪70年代末、80年代末-90年代初和21世纪初发生雨带的南北移动过程,其中夏季雨带的移动主要受东亚夏季风和大气环流年代际变化的影响。西北地区降水以1985/1986年为突变年,西北西部地区降水由前期偏少转为偏多,主要与来自阿拉伯海和里海异常偏多的水汽输送有关;西北东部地区降水由前期偏多转为偏少,主要与季风的年代际减弱有关。东北地区降水在80年代初由前期接近正常转为偏多,90年代末降水由前期偏多转为偏少,主要与季风和西北太平洋水汽输送的年代际变化相关。西南部各区降水阶段性变化明显,2000年以前西南东北部地区降水与西部地区基本呈反向变化,主要受青藏高原地形、东亚季风和副热带高压等因素的影响,降水阶段性变化明显、成因复杂。

Based on precipitation data from 1840 meteorological stations in China in 1960-2010, this study examines the regional differentiation of precipitation and characteristics of its change in the recent 50 years. Using the empirical orthogonal function (EOF) and rotated EOF (REOF) methods, precipitation in China is divided into 11 regions, which are grouped into four areas according to their geographic locations: East China area (North China, Huanghuai and Jianghuai, the middle and lower reaches of the Yangtze River, and Jiangnan and South China regions), Northwest China area (Midwest Inner Mongolia, western part of the Northwest China, and eastern part of the Northwest China regions), Southwest China area (southeastern part of the Southwest China, western part of the Southwest China, and northeastern part of the Southwest China regions), and Northeast China. Compared with the results of previous studies, precipitation regions derived with the REOF method in combination with detailed long time series precipitation data are consistent with the regional differentiation of actual precipitation and the climate division of China. The analysis shows that precipitation in the East China area changed in the late 1970s, from the late 1980s to the early 1990s, and in the beginning of the 21st century respectively, featuring recurrent south-north shifts of the rain belt in both directions, which were mainly influenced by the interdecadal variability of the East Asian summer monsoon and atmospheric circulation. Precipitation in the Northwest China area experienced a major change in the mid-1980s. The western part of the Northwest China area became wet compared to the dry period in the previous years, whereas the eastern part of the area became dry compared to the previous wet years. The decreasing precipitation in the eastern Northwest China area was related to the continually weakening of the East Asia summer monsoon, while the increasing precipitation in the western Northwest China area were mainly due to the anomalous high moisture transport from the Arabia Sea and the Caspian Sea. Precipitation in the Northeast China area underwent similar abrupt changes in the early 1980s and the late 1990s respectively-it changed from the previous near normal level to high in the early 1980s, and from high to low in the late 1990s. The changes were influenced by the East Asian summer monsoon on the one hand, and related to the anomalous moisture transport form the Northwest Pacific Ocean on the other. Evident changes in precipitation have been detected over each region in the Southwest China area-precipitation changes over the western and northeastern parts of this region were in opposite directions before 2000. Precipitation in the Southwest China area is not only influenced by the terrain of the Tibetan Plateau, but also affected by the East Asian monsoon and the subtropical high, which cause complicated changes in precipitation of the area.

The authors have declared that no competing interests exist.