基于幂律分布的山西省降水变化特征分析

Analysis of the Power-law Exponent of Shanxi Precipitation

本文利用山西省109个地面气象站1980—2015年5—9月的日降水观测资料，对其在等级分析的基础上探讨了幂律分布的规律，最终得到以下结论：①山西各个地区均存在一个共同特征-幂律尾分布特征，且在不同的降水段幂律尾指数不一样，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；②对于小雨而言，降水量以90年代中期为转折点，北部和中部小雨降水总量减少，西南东南比之前增加；③对于中雨而言，80年代初期，各个地区中雨降水总量减少，80年代初到80年代末中部和西南部降水减少，北部和东南部降水增多；80年代末到90年代中期，东南和中部中雨降水总量减少，西南部降水总量增加，北部降水总量先减后增；90年代中期之后，除北部中雨降水总量减少以外，其他地区降水总量均增加；④小雨段幂指数变化相对于中雨段较小，中雨雨量的变化对总雨量的变化贡献更突出。

The daily precipitation observational data of 109 stations of Shanxi in May to September from1980a to 2015a are divided in sections, statistically and power-low distribution analyzed. The result shows that, （1）There is a common feature in all regions of Shanxi-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; （2）For the light rain, the precipitation in the northern and central region were decreased, and in the southeast and southwest were increased after the mid 1990s; （3）For the moderate rain, the P d recipitation in all the regions were decreased in the early 1980s. and in the central region and southwest were ecreased , while in the north and southeast were increased from the early 1980s to the late 1980s, and the precipitation in the southeast and central region were decreased, while in the southwest was increased, and in the north was decreased first and then increased from the late 1980s to the mid 1990s,the precipitation in the north was decreased ,and other regions were increased after the mid 1990s ;（4）The light rain exponent is changed very little over time, but the moderate power exponent ischanged dramatically.So the changes of total precipitation may be caused by the moderate power changes.