区域性暴雨过程评价指标在湖北的本地化修订与应用

Localized revision and application of assessing indices for regional heavy rainfall events in Hubei Province

基于中国气象局2019年下发的《区域性重要过程监测和评价业务规定》,针对其中区域性暴雨过程监测和评价方法,为便于区域性暴雨过程间的比较,对其相关指标进行本地化修订,将修订后的评价指标应用于近50 a湖北区域性暴雨过程评价。首先,利用1969—2018年湖北省81个国家级地面气象观测站逐日降水数据,定义了湖北区域性暴雨日和区域性暴雨过程;然后,以区域性暴雨过程平均暴雨强度、平均影响范围和持续日数为评价因子,确立湖北区域性暴雨过程综合强度评价指标,以百分位法划分其评价等级,再以正态分布函数拟合区域性暴雨过程重现期;最后,分析近50 a湖北区域性暴雨过程发生频次、强度及其气候变化特征,利用历史上主要暴雨过程致灾损失数据验证评估结果的合理性。结果表明:(1)综合应用湖北本地化判定方法显示,近50 a湖北发生723次区域性暴雨过程,年发生9~23次,年均14.5次,其年变化趋势不显著。1990年代中期以来,持续1~2 d的过程呈增加趋势,持续3 d以上的过程趋于减少;自21世纪以来,湖北特强和强区域性暴雨过程呈减少趋势,较强及弱过程呈增加趋势。(2)近50 a湖北10强区域性暴雨过程主要发生在20世纪;修订后的基于气象要素的评价指标的评价结果能够反映承灾体致灾损失实际,可用于灾后损失的预估和快速量化评估。(3)中国气象局确定的省级区域性暴雨过程监测与评价指标经本地化修订后能够用于湖北区域性暴雨过程的监测与评价。

Based on the operational provisions of important regional weather event monitoring and evaluation issued by CMA in 2019,in terms of the monitoring and evaluation method for regional heavy rainfall event within,also for being easy to compare the different regional heavy rainfall events,we have conducted a localized revision to the relative indices,and applied the corrected assessing indices to the assess⁃ment of regional heavy rainfall events in Hubei province.Firstly,using daily precipitation data at 81 national weather stations in Hubei from 1961 to 2018,the regional heavy rainfall day and the regional heavy rainfall event in Hubei were defined.Secondly,average heavy rainfall in⁃tensity,average covering area and duration of a regional heavy rainfall event were selected as the assessing factors by which the synthesizing assessing index is established for the regional heavy rainfall events in Hubei,and then the synthesizing intensity grades were divided by per⁃centile method to simulate the intensity recurrence interval of regional heavy rainfall process by the normal distribution function.Thirdly,the frequency and intensity and the climatic change characteristics of regional heavy rainfall events were analyzed in the recent 50 years in Hu⁃bei.The validity of assessment was verified by the loss data of main regional heavy rainfall events.The results show that the 723 regional heavy rainfall events occurred in the recent 50 years in Hubei,and there are from 9 times to 23 times a year,with their annual change tenden⁃cy being not significant,according to the localized criterion of monitoring index.But after the mid-1990s,the events lasting 1 or 2 days have an increasing trend,while those lasting more than 3 days have a decreasing trend.After 21st century,the extra strong and strong regional heavy rainfall events in Hubei tend to decrease,and the events being ordinary and weak tend to increase.The top 10 events in Hubei hap⁃pened mainly in 20th century.The monitoring and evaluation indices to provincial regional heavy rainfall events issued by CMA in 2019 can be used in the monitoring and assessing such events in Hubei after the localized revising.