我国雷暴天气的气候特征

A STUDY ON CLIMATIC FEATURES AND ANOMALIES OF THE THUNDERSTORM IN CHINA

利用我国３０年历年雷暴日资料，采用ＥＯＦ和主值函数分析等方法，对我国年平均雷暴日的时空分布特征及其异常变化进行了研究。结果表明：年平均雷暴日的分布大致可分为４个区域。第一载荷向量在空间上具有较好的一致性，方差贡献为３５．１％，在黄河中下游地区有所差异。３０年来雷暴日总体在波动中呈减少趋势，但是在某些地区某些时段却有相反的变化，距平场的年代变化特征和各代表区域年平均雷暴日距平序列均说明了以上的结论。

The diagnostic studies for the features of spatial and temporal distribution of the annual mean thunderstorm in China are made with EOF and main function analysis by using 30 year data from 104 observational stations. Results show that the distribution of thunderstorm in China is divided into 4 regions. The highest is in South and Southeast of China, the second in Tibet plateau and where nearby it, the third in North and center of China, the lowest in Northwest of China. The variation of first loading vector of the annual mean thunderstorm has spatial consistency.The variance ratio contribution of the first principal component is about 35.1%. However, the thunderstorm frequencies under different geographical conditions are of difference. Analysis indicates that the general trend of the annual mean thunderstorm change has been reducing for the last 30 years.It is obvious that the thunderstorm frequency became little over the majority region in 1980s except the Northeast part of the Northeast region and the Northwest part of the Xinjiang province.