基于幂律尾指数研究中国降水的时空演变特征

基于中国气象局国家气候中心740站点1960—2000a的日降水观测资料，对中国各地区日降水量分等级进行统计分析，揭示了各地区日降水存在的一个共同特征——幂律尾分布，且不同等级的降水量对应不同的幂律尾指数，在一定程度上反映了不同雨型具有不同的气候背景和物理机理.中国华北、华南等七个气候特征区，其幂律尾指数总体自东南向西北呈递增趋势，这与中国降水东多西少，南多北少的空间分布特征相符合.研究各气候特征区日降水的幂律尾指数随时间的演变特征发现：东北、华北和西北地区的幂律尾指数发生突变的年份对应着20世纪70年代末开始的中国北方干旱化进程，导致的可能原因是微量降水，尤其是0—7mm日降水的减少. 关键词： 幂律尾指数 突变 北方干旱化

Analysis of the spatio-temporal characteristics of precipitation of China based on the power-law exponent

The daily precipitation observational data of 740 stations from 1960a to 2000a Which provided by National Climate Center of Chinese Meteorologial Administration, are divided in sections and statistically analyzed. A common feature is revealed the power-law distribution, and different precipitation corresponds to different power-law exponent; this to a certain extent reflects that different precipitation have different climate backgrounds and control systems. The power-law exponents of the seven climate regions of China show the trend of increase from southeast to northwest, this corresponds to the spatial characteristic of precipitation of China more in east and less in west, more in south and less in north. The analysis on the characteristic of the temporal evolvement of the power-law exponent shows that the abruption points of the power-law exponent of northeast, east, and northwest of China correspond to the drying trend of northern China starting from 1970s.