德江县极端降水事件特征及天气模型

Characteristics of extreme precipitation events and weather models in Dejiang County

该文利用1959—2018年德江国家站、1987—2017年思南和沿河国家站、2010—2017年德江县19个区域站的逐日降水数据,采用95位百分位法定义极端降水事件发生阈值,运用统计学方法分析德江县极端降水事件频数和强度的特征,基于M-K非参数检验方法对极端降水事件频数和强度长期变化趋势进行检验。研究近60 a乌江中下游流域德江站极端降水频数和强度的特征和关系,再研究近8 a德江县19个区域站极端降水事件特征,结果表明,乌江中下游流域德江站近60 a来发生极端降水事件阈值为30.7 mm,平均极端降水频数为8.7 d,平均极端降水强度为52.6 mm/d,近60 a年来德江县发生极端降水事件的频数和强度总体呈现上升的趋势,近8 a德江县中部、北部、西北部、西南部乡镇出现平均极端降水频数天数较多,近8 a德江县乌江流经段东南部乡镇平均极端降水降水强度较强,日降水量>100 mm的极端降水事件主要集中出现在6月和7月,典型极端降水事件年发生概率为38%。选取乌江中下游流域思南、德江、沿河3站近10 a典型极端降水事件为研究对象,综合分析各层次天气系统,归纳总结出乌江中下游流域极端降水天气模型。

Based on the daily precipitation data of Dejiang National station from 1959 to 2018,Sinan and Yanhe national Station from 1987 to 2017 and 19 regional stations of Dejiang County from 2010 to 2017,the 95th percentile method was adopted to define the threshold of extreme precipitation events and statistic methods was used to analyze the occurence frequency and intensity characteristics of the extreme precipitation events of Dejiang County.The long-term variation trend of extreme precipitation event frequency and intensity was tested by MK nonparametric test method.The characteristics and relations of extreme precipitation frequency and intensity at Dejiang station in the middle and lower Wujiang River basin of nearly 60 a were studied,and then the extreme precipitation event characteristics of 19 regional stations in Dejiang county of nearly 8 a were studied.The results show that the threshold value of extreme precipitation events in Dejiang station in the middle and lower reaches of Wujiang river is 30.7 mm,the average frequency of extreme precipitation is 8.7 days,and the average intensity of extreme precipitation is 52.6 mm/d.In the past 60 a,the frequency and intensity of extreme precipitation events in Dejiang county generally showed an upward trend.The average frequency of extreme precipitation in the central,northern,northwestern and southwestern towns of 8 a Dejiang county was more days,and the average intensity of extreme precipitation in the southeastern towns in the Wujiang river flowing through section of 8 a Dejiang county was relatively strong.Extreme precipitation events with a daily precipitation of more than 100 mm mainly occurred in June and July,and the annual occurrence probability of typical extreme precipitation events was 38%.The typical extreme precipitation events in Sinan,Dejiang and Yanhe stations in the middle and lower reaches of the Wujiang river were selected as the research object.The weather systems at all levels were comprehensively analyzed,and the extreme precipitation weather model of the middle and lower reaches of the Wujiang river was summarized.