气象2025，Vol.51Issue(6)：686-699,14.DOI:10.7519/j.issn.1000-0526.2025.012301
鄂西地区一次低层锋生背景下的极端强降水MCS组织化观测分析
Analysis of the Organization of Extreme Severe Rainfall MCS Under a Low-Level Frontogenesis Background in Western Hubei Province
摘要
Abstract
An extreme torrential rain event caused by highly organized severe rainfall mesoscale convection system(MCS)occurred in Yichang on 22 April 2018.Based on conventional observation data,observation data from regional automatic weather stations,radar data and ERA5 reanalysis data,we analyze the organ-izational characteristics and formation mechanism of extreme severe rainfall MCS.The results are as fol-lows.This extreme torrential rain event occurred under the background of weak forcing at high level and weak forcing turning into strong forcing at low level,accompanied by strong frontogenesis.High tempera-ture,high humidity and extremely unstable atmospheric environment were conducive to the occurrence of the extreme severe rainfall.The warm and wet easterly air at low level was forced to lift by the C-pattern terrain in the east of Yichang,triggering the severe rainfall echoes in the transition area from mountain to plain.The warm and wet southeasterly or easterly wind at top of the boundary-layer reverted warm trough caused the dispersed flocculent convection in the plain area from Yidu to Gongan.The organization of ex-treme severe rainfall MCS experienced merging stage and vortex stage.Under the influence of weak synop-tic-scale forcing,MCS in the mountain-to-plain transition area spread to southeast along the low-lying ter-rain,and merged along three paths with the warm area flocculent echoes from the plain to north.The east-west MCS formed by the low-level east-west frontal zone and the surface convergence line moved toward west under the guidance of the middle and low level easterly jet,and continuously merged with the south-north MCS in the mountain-to-plain transition area peristently,resulting in the heaviest precipitation stage.The mesoscale cyclonic circulation,composed of MCS cold outflow and ambient airflow,and the la-tent heat of severe rainfall that heated the middle atmosphere favored the organization,development and strengthening of vortex MCS.The water vapor energy transport of the low-level warm and wet easterly jet was beneficial to the long-time maintenance of the vortex MCS.The extreme severe rainfall mainly oc-curred in the merging stage and the long-time vortex stage of MCS.Synoptic-scale system forcing,low-level strong frontogenesis,mesoscale topography and positive feedback of mesoscale weather system were the important causes of the formation for this extreme severe rainfall.关键词
极端暴雨/强降水MCS/组织化/弱强迫/锋生Key words
extreme torrential rain/severe rainfall MCS/organization/weak forcing/frontogenesis分类
大气科学引用本文复制引用
章翠红,黄小彦..鄂西地区一次低层锋生背景下的极端强降水MCS组织化观测分析[J].气象,2025,51(6):686-699,14.基金项目
湖北省自然科学基金项目(2022CFD121)、中国气象局创新发展专项(CXFZ2025J028)和湖北省气象局科技发展基金项目(2022Z01)共同资助 （2022CFD121）
