昆山市暴雨时空分布特征及设计暴雨强度公式推求

基于江苏省昆山市2008—2015年12个自动气象站逐分钟降雨数据和常规气象站小时降雨量数据，并选取5个代表站分别代表不同的生态系统，先对昆山市降雨和暴雨的时空特征进行分析，然后采用年多个样法进行暴雨选样，利用指数分布、皮尔逊Ⅲ型分布和耿贝尔分布分析暴雨发生频率，最后使用高斯-牛顿法推求不同生态系统代表站的暴雨强度公式参数，结果表明:(1)昆山市各站点2008—2015年期间年降雨量都呈增长趋势，夏季降雨量最多、冬季最少，一天中01时(北京时间，下同)左右为降雨谷值，18时左右为降雨峰值，白天降雨多于夜晚; 在空间分布上，农田和城市生态系统的年降雨量、年降雨日数最多，湿地和湖泊生态系统较少。(2)暴雨日数年际差异大，年内暴雨主要集中在夏季，暴雨发生频次日变化呈“双峰型”分布，暴雨发生频次在02时和18时最多，09时和24时最少; 市区的暴雨日数空间变异系数大于郊区，且从市中心向外递减。(3)城市生态系统适宜采用皮尔逊Ⅲ型分布推求暴雨强度公式，其他类型生态系统适宜采用指数分布推求暴雨强度公式。 

SPATIO-TEMPORAL CHARACTERISTICS OF RAINSTORM IN KUNSHAN AND RECKONING OF DESIGNED RAINSTORM INTENSITY FORMULA

Based on the minute-by-minute precipitation data from 12 automatic weather stations and hourly rainfall data from conventional weather stations in Kunshan City from 2008 to 2015, and by selecting five stations to represent different ecosystems, the present study analyzed the spatio-temporal variation characteristics of precipitation and heavy rain in Kunshan City. Multiple rainstorm samples were selected, and the frequency of rainstorm was analyzed by using methods such as exponential distribution, Pearson type III distribution and Gumbel distribution. Finally, the Gauss-Newton method was used to estimate the rainstorm intensity formula parameters of different stations selected to represent ecosystems. The results are as follows. (1) The annual precipitation of each station in Kunshan had an increasing trend during the period of 2008—2015. As for seasonal variation, the precipitation of each station was more in summer and less in winter. In terms of diurnal variation, the valley value of precipitation was reached around 1:00, and the peak value of precipitation was reached around 18:00. The precipitation during daytime was relatively more than that at night. In terms of spatial distribution, the annual precipitation and annual precipitation days of farmland and urban ecosystems were the largest, and those of wetland and lake ecosystems were small. (2) The number of rainstorm days varied greatly from year to year and the rainstorm mainly occurred in summer. The daily variation of the frequency of rainstorm showed a "double-peak" distribution: rainstorms occurred most frequently around 2:00 and around 18:00, and least frequently around 9:00 and around 24:00. The spatial variation coefficient of urban rainstorm days was larger than that of the suburbs, and it decreased from the downtown to peripheral areas. (3) Pearson type III distribution is suitable to derive the rainstorm intensity formula for the urban ecosystem, and exponential distribution is suitable to derive the rainstorm intensity formula for other types of ecosystems.