北京地区降水结构时空演变特征

Spatial-temporal variation characteristics of precipitation pattern in Beijing

利用北京地区42个雨量站1980—2012年的小时降水数据,采用降水发生率和降水贡献率两个指标,分析不同降水历时和不同降水等级的时空演变规律以及北京地区降水日变化特征。利用非参数的Mann-Kendall检验法探讨降水结构的变化趋势,结合地形特征和城市化发展情况,本文将研究区域经验性地划分为6个子区域,评估降水历时和降水等级的空间变化特征。研究结果表明：（1）北京地区各历时降水发生率随降水历时的增加而呈幂指数递减趋势,贡献率则先降低后增加;（2）北京地区各等级降水发生率也随着等级提高而减小,而贡献率则呈现增加趋势;（3）1~3 h超短历时降水发生率在1990年代开始下降,而其他历时降水发生率则呈增加趋势,6 h以内短历时降水贡献率存在增加趋势,特别是4~6 h历时的降水贡献率变化更为显著;（4）小雨发生率存在下降趋势,其他等级降水发生率则呈增加趋势,大雨及以下等级的降水贡献率先降后升,而暴雨和大暴雨的降水贡献率则先升后降;（5）降水历时和降水等级的空间分布受地形特征的影响,短历时降水和暴雨及其以上等级降水贡献率的峰值一般位于平原地区与山区的边缘地带及城市区域。

On basis of quality-control of hourly precipitation data from 42 rain-gauge stations over Beijing area from 1980-2012, the spatial-temporal variation and diurnal characteristics of precipitation pattern dur- ing the rainy season in Beijing were analyzed. The incidence rate and contribution rate of precipitation are defined and used to assess the spatial and temporal variation of precipitation pattern in Beijing. The Mann-Kendall test method is used to discuss the trend of precipitation pattern. In addition, the differences in spatial variation of precipitation are investigated in six sub-regions, which are distinguished empirically based on underlying surface conditions and urban development. The results show that： （~）the incidence rate of precipitation events for different durations decreases power- exponentially with the increase of precipita- tion durations, while the corresponding contribution rate firstly decreases and then increases; （2）the inci- dence rate for different grades decreases with the increase of precipitation grades, while the corresponding contribution rate is increasing; （3）the downward trend is found in the incidence rate for 1-3 h duration, while the upward trend is detected in other durations, and also in the contribution rate for the short-dura- tion precipitation events, especially for 4-6 h duration precipitation events; （4）there is a decreasing trend for the incidence rate of light rain events, while the opposite is true for the other four grades, and the contribution rates of precipitation for light, moderate and heavy rain events are found to be decreasing and then increasing, while the opposite trend is found for storm and torrential rain events; （5）the spatial characteristics of precipitation durations and grades are influenced by the topographical characteristics, and the high-record center of the contribution rate short-duration precipitation and extreme heavy precipitation events locates in the plain area and the urban area.