Fine analysis of precipitation climate characteristics in Lishui district
溧水区降水气候特征精细化分析

摘要

溧水区属典型湿润气候，68年年降水量呈现右偏分布，密集核心区为850-1300mm，存在极端波动，降水量以每十年49.4mm的速度上升，且2010年代后增速加快。现行降水百年一遇阈值为1730mm，2030年调至1779.4mm，后期需建立5年周期阈值修订机制。有效降水日数呈现显著年际波动特征，无长期变化趋势，1976年的突变事件导致降水日数均值降低1.7天，而2010年后波动性增强与极端高值频现。夏季（6-8月）降水量占全年主导地位，其中6月、7月呈现显著上升趋势而5月的显著下降趋势反映出季风推进过程的气候变异。9月降水量显著上升而8月趋势不显著，可能关联夏季风撤退推迟及台风路径变化。小时尺度监测对短时强降水识别能降低暴雨事件的遗漏率，暴雨强度呈现显著离散特征，其中25%事件超过25.3mm/h预警阈值，监测到4次超47.5mm/h极端值，更凸显精细化观测的重要性。

Abstract

Lishui District belongs to a typical humid climate, with 68 years of precipitation showing a right skewed distribution. The dense core area ranges from 850-1300mm, with extreme fluctuations. Precipitation increases at a rate of 49.4mm per decade, and the growth rate has accelerated since the 2010s. The current threshold for once-in-a-century precipitation is 1730mm, and it will be adjusted to 1779.4mm in 2030. A 5-year cycle threshold revision mechanism needs to be established in the later stage. The number of effective precipitation days shows significant interannual fluctuations with no long-term trend. The sudden event in 1976 led to a decrease of 1.7 days in the average number of precipitation days, while after 2010, the volatility increased and extreme high values appeared frequently. The precipitation in summer (June August) dominates the whole year, with a significant upward trend in June and July and a significant downward trend in May reflecting the climate variation during the monsoon advance process. The precipitation in September significantly increased while the trend in August was not significant, which may be related to the delay of summer monsoon retreat and changes in typhoon path. Hourly scale monitoring can reduce the omission rate of rainstorm events by identifying short-term heavy precipitation. The intensity of rainstorm shows significant discrete characteristics, of which 25% of events exceed the warning threshold of 25.3mm/h, and four times of monitoring exceed the extreme value of 47.5mm/h, which highlights the importance of fine observation.