中国近50a极端降水事件变化特征的季节性差异

Seasonal Differences of Variation Characteristics of Extreme Precipitation Events over China in the Last 50 Years

利用中国419个测站1958—2007年逐日降水资料集,分析了近50 a中国不同区域年和季节极端降水事件的基本变化特征。结果表明,多年平均极端降水事件的空间分布具有明显的纬向分布特征,并表现出显著的季节性差异。长江以南地区是春、冬季极端降水事件发生频次较高的区域;而年、夏季以及秋季极端降水事件发生频次在西南地区较高,在西北东部较低。年极端降水事件频次的长期变化趋势与夏季相似,华北和东北有增加趋势,其他地区为弱的减少趋势;其他季节的长期变化趋势存在明显的区域和季节性差异。年和季节极端降水事件的发生频次具有显著的年际和年代际变化特征。年极端降水事件时间序列的多项式拟合曲线的变化情况与夏季基本一致;而其他季节的变化则存在较大差异,表现出显著的季节性差异。

By using the 1958-2007 daily rainfall data of 419 stations in China,the basic characteristics of seasonal extreme precipitation events over sub-region in China during the last 50 years are investigated. Results show that： （1） Evident zonal distribution and significant seasonal differences are found in the spatial distribution of the climatological extreme precipitation events. The frequency of extreme precipitation events in the south of the Yangtze River is higher in spring and winter. Howerver, the frequency is higher over Southwest China but lower in the east of Northwest China, in annual, summer and autumn cases.（2）The longterm trend of annul extreme precipitation events is similar to that in summer. An increasing trend is also found in North China and Northeast China, but decreasing trends in other regions.（3） The frequencies of extreme precipitation events in different seasons exhibit significant in- terannual and interdecadal variabilities. The polynomial fitting curves of the time series of annual extreme precipitation events are consistent with that of the summer in most cases, and the variability of extreme precipitation events in other seasons shows great diversity as well as evident seasonal difference.