北京相当暴雨日数的气候特征

根据北京99年6～8月的逐日降水资料和274年6～8月总降水量资料， 分析了相当暴雨日数与总降水量及旱涝等级的相关性，给出相当暴雨日数与总降 水量的定量关系式，建立了北京274年汛期相当暴雨日数资料序列。分析表明: 相当暴雨日数概念的引入，可以把汛期总降水量中暴雨过程降水与非暴雨过程降 水分开，证实汛期旱涝变化只取决于暴雨过程的总次数和强度；相当暴雨日数是 一个气候统计量，有与总降水量一致的周期变化，但其年际变率和3.5年周期比 总降水量更显著，其概率分布满足泊松分布；与旱涝等级比较，相当暴雨日数与 总降水量的相关性更好，且有利于研究形成汛期旱涝灾害的暴雨过程特征。

Climatological Features for the Number of the Equivalent Torrential Rain Days in Beijing

Based on daily precipitation data of June-August in 99 years and monthly precipitation data in 274 years in Beijing, the correlation of the number of the equivalent torrential rain days and the dryness and wetness grades in the flood season is analysed, the quantitative correlation for the number of the equivalent torrential rain days and the total procipitation of June-August is given The data series of 274 years for the number of the equivalent torrential rain days is built It is seen that the concept for the number of the equivalent torrential rain days can differentiate the precipitation of the torrential rain and the precipitation of the non-torrential rain, and the dryness and wetness change in flood season is determined only by the number and the strength of the torrential rain processes The number of the equivalent torrential rain days is the climatologically statistical quantity It is the same periodic variation with the total procipitation of June-August, but the interannual variability and a 3 5-year periodic for the number of the equivalent torrential rain days are more notable The probability distribution for the number of the equivalent torrential rain days satisfies the Poisson distribution The number of the equivalent torrential rain days can be used to research on the feature of the torrential rain processes of drought and flooding