摘要
利用常规气象资料、加密自动站资料、NCEP 1°×1°逐6 h再分析资料、FY-2E卫星资料及开封气象观测站19812016年的日降水量资料,分析了开封“7·19”大暴雨的环流背景及水汽、动力等环境因子的极端性。结果表明:副热带高压稳定加强、高空低槽东移加深,引导中低层低涡切变线加强东北移和地面倒槽发展,诱发中小尺度辐合中心及辐合线的形成与维持,从而触发了本次大暴雨天气的发生。采用百分位法定义开封夏季极端降水阈值,“7·19”大暴雨日降雨量位居近20年首位,居1981年以来第4位,超过极端降水阈值的2倍,具有明显的极端性;动力和水汽条件极端性强,700 hPa和850 hPa垂直速度极值创2000年以来暴雨过程之最,与历年暴雨个例差值分别达-6.9σ、-4.7σ,850 hPa和925 hPa的水汽通量≥25 g·cm^(-1)·hPa^(-1)·s^(-1),整层可降水量达75 mm,居2000年以来暴雨过程第一位。通过HYSPLIT-4后向轨迹模拟,“7·19”极端暴雨的水汽来源主要为南海,其次是孟加拉湾,且3000 m高度以下水汽输送贡献率达到85%以上。
Based on the conventional meteorological data,densely-observed automatic station data,NCEP 1°×1°6 h reanalysis data,FY-2E satellite data and daily precipitation data of Kaifeng meteorological station from 1981 to 2016,this paper analyzes the circulation background of the“7·19”severe rainstorm in Kaifeng,Henan province,as well as the extremity of the rainstorm from the aspects of water vapor and dynamic conditions.The results show that during the heavy rainstorm,the subtropical high strengthened stably,and the upper-air low trough moved eastward and deepened,which guided the vortex shear line of the middle and lower level to move northeast and the surface inverted trough to develop and induced the formation and maintenance of meso-scale and small-scale convergence centers and convergence lines,thus triggering the occurrence of the severe rainstorm.The percentile method is used to define the threshold of summer extreme precipitation in Kaifeng.The daily rainfall of the“7·19”severe rainstorm ranked the first in the recent 20 years and the fourth since 1981.It was more than twice of the threshold of extreme precipitation,showing obvious extremity.The extreme features of dynamic and water vapor conditions were strong.The maximum vertical velocity at 700 hPa and 850 hPa was the highest in the rainstorm processes since 2000,and the difference between them and the individual rainstorm cases in previous years was-6.9σand-4.7σ,respectively.The water vapor flux at 850 hPa and 925 hPa was≥25 g·cm-1·hPa^(-1)·s^(-1).Atmospheric precipitable water of the whole layer reached 75 mm,ranking the top in the rainstorm processes since 2000.According to the backward trajectory simulation of HYSPLIT-4,the water vapor source of the“7·19”extreme rainstorm was mainly the South China Sea,followed by the Bay of Bengal,and the contribution rate of water vapor transport below the 3000 m height reached more than 85%.
作者
冀翠华
李姝霞
Ji Cuihua;Li Shuxia(Kaifeng Key Laboratory of Meteorological Disaster Prevention and Mitigation, Kaifeng 475004, China;Kaifeng Meteorological Office, Kaifeng 475004, China)
出处
《气象与环境科学》
2021年第4期53-62,共10页
Meteorological and Environmental Sciences
基金
中国气象局预报员专项(CMAYBY2019-070)
河南省气象局重点项目(Z201601)
河南省科技攻关项目(172102310463)
开封市重点(重大)科技计划项目(192D012)。
关键词
大暴雨
极端性
水汽输送贡献
物理量阈值
severe rainstorm
extremity
contribution of water vapor transport
physical quantity threshold
