北京市通州区降雨时空特征分析

利用1973 — 2018年通州区17个气象站的逐日降雨数据，统计小、中、大、暴雨4个等级降雨发生频次和降雨累积值，分析不同等级降雨空间分布特征；采用百分位阈值法、滑动平均法等方法，分析极端降雨阈值及时空演变规律. 结果表明:1）通州区降雨95%阈值范围为44.1~50.2 mm，99%阈值范围为74.5~93.5 mm，99%阈值更能体现极端降雨事件.2）99%阈值的极端降雨发生在6 — 9月，主要在8月上旬、7月下旬、6月底7月初. 宋庄镇北部和西集镇东部较易发生极端降雨事件；副中心范围内的张家湾镇北部和潞城镇西北部较易发生极端降雨事件.3）极端降雨发生的频次整体呈减小趋势，北部和东部呈上升趋势，西南地区呈下降趋势，在空间上有明显的分界线.4）西集镇东部极端降雨频次、极端降雨量和极端降雨量贡献率不仅处于较高值，而且年际变化呈上升趋势，应为重点关注区域. 

Temporal and spatial characteristics of precipitation in Tongzhou District,Beijing

Daily precipitation data at 17 weather stations in Tongzhou District from 1973 to 2018 were used to calculate frequency of occurrence and precipitation cumulative value of four grades of light rain, moderate rain, heavy rain, torrential rain, and spatial distribution characteristics of different grades of precipitation were analyzed. Percentile threshold method, moving average method and other methods were used to analyze extreme precipitation threshold, temporal and spatial evolution of extreme precipitation. The 95% threshold range of Tongzhou District was found to be 44.1~50.2 mm, 99% threshold range 74.5~93.5 mm. The 99% threshold was found more representative of extreme precipitation events. Extreme precipitation of 99% threshold was found to occur from June to September, mainly in early August, mid-late July, end of June and beginning of July. Extreme rainfall events were found to be more likely to occur in northern part of Songzhuang Town and eastern part of Xiji Town. In sub-center, extreme rainfall events were found to be more likely to occur in northwestern part of Zhangjiawan Town and northwestern part of Lucheng Town. The frequency of extreme precipitation was found to decrease as a whole, but increase in the north and east, decrease in the southwest, with a clear spatial dividing line. In the east of Xiji Town, precipitation frequency, extreme precipitation and contribution rate of extreme precipitation were found to be not only at a high value, but also showed an increasing trend of interannual change, therefore it should be the focus area.