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2020年6-7月长江中下游地区梅汛期强降水的极端性特征
张芳华1, 陈涛1, 张芳1, 沈晓琳1, 蓝渝2
(1.中国气象局国家气象中心;2.国家气象中心)
Extreme Features of Severe Floods in the Middle and Lower Reaches of Yangtze River Basin during Meiyu Period in June-July 2020
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投稿时间:2020-08-07    修订日期:2020-09-02
中文摘要: 2020年6-7月长江中下游地区发生了极为严重的洪涝灾害,本文基于国家站长时段逐日降水资料、国家站和区域自动站小时降水资料等分析了强降水的极端性特征。长江中下游地区降水异常偏多的范围明显大于1998年和2016年同期,仅次于1954年。大别山区、皖南山区和鄂西南山区是三个雨量大值中心,最大累计降雨量均在1500 mm以上。降水的异常偏多与强降水长时间维持在长江中下游地区密切相关。2020年长江中下游梅雨期历时53日,较常年偏多23日,且是1961年以来唯一一年6-7月逐旬降水均偏多的年份。不同等级雨日的分析表明,该年中雨、大雨、暴雨、大暴雨及以上站次均为1961年以来同期最多,后三种等级偏多更为显著。强降水的极端性同样体现在小时尺度的短历时降雨中,2020年6-7月长江中下游地区出现大于等于20 mm/h和50 mm/h短时强降水的累计站日数分别为1612和100,均列1981年以来的同期第一位;强降水中心的黄山、祁门、岳西和鹤峰站小时降水超过20 mm的时次数是常年同期的2~4倍,各自前43、21、19和27次最强小时降水累加即超过常年6-7月累计降水量。上述结果表明,2020年6-7月长江中下游地区梅汛期强降水在总雨量、持续时长及雨强等方面均具有明显的极端性特征。
Abstract:Severe flood occurred in the middle and lower reaches of the Yangtze River Basin (MLYRB) in June-July 2020 (JJ2020). In this paper, the extreme features of the flood are analyzed based on daily precipitation observation at national stations from 1951 and hourly observation at national & regional stations in JJ2020. Both the flood range (anomaly percentage more than 50% or 100%) and the total amount are significantly greater than those in 1998 and 2016, and ranked the second in recent 70 years followed 1954. There are three rainfall centers with maximal accumulated precipitation greater than 1500 mm, including Dabie Mountain area, Southern Anhui Province and southwestern Hubei Province. The flood is closely related to the extreme long-term persistence of Meiyu in MLYRB. The Meiyu period in 2020 lasts for 53 days, 23 days more than the climatology. In JJ2020, positive precipitation anomaly existed in each dekad, which was never occurred before since 1961 and also indicates the extreme features of the flood. Total station numbers in JJ2020 are all the maxima since 1961 at four different rainfall grades (i.e., 10-24.9 mm/day, 25-49.9 mm/day, 50-99.9 mm/day and ≥ 100 mm/day), especially in the latter three grades. Extremity of the flood can also be found in the short-duration heavy rain processes. In JJ2020, the accumulated station number is 1612 and 100 with hourly precipitation over 20 mm and 50 mm, respectively. Both of the numbers are the highest since 1981. At four stations with total precipitation exceeding 1500 mm, frequencies of hourly precipitation greater than 20 mm are 2~4 times to their climatologies. Accumulation of the first 43, 21, 19 and 27 strongest hourly precipitation exceeds their seasonal average, respectively. Above results indicate the significant extremity of the flood in MLYRB existed in the total rainfall, the duration and the short-term intensity.
文章编号:202008070281     中图分类号:    文献标志码:
基金项目:中国气象局暴雨预报专家创新团队专项(CMACXTD002-3)和国家科技支撑计划课题(2015BAC03B04)共同资助
引用文本:
张芳华,陈涛,张芳,沈晓琳,蓝渝,.[en_title][J].Meteor Mon,():-.
ZHANG Fanghua,CHEN Tao,ZHANG Fang,SHEN Xiaolin,LAN YU,.Extreme Features of Severe Floods in the Middle and Lower Reaches of Yangtze River Basin during Meiyu Period in June-July 2020[J].Meteor Mon,():-.