湖北省夏季引发极端降水的MCS统计特征分析

Statistical characteristics of extreme precipitation induced by MCS in Hubei Province

利用2008—2018年4—9月新一代天气雷达资料,挑选了引发湖北省极端降水过程的70例中尺度对流系统(mesoscale convective systems,MCS),重点研究了线状MCS成熟阶段的时空分布特征,结果表明:(1)5类线状MCS中邻接层状云降水AS(adjoining stratiform)发生比例最高,前导层状云降水LS(leading stratiform)、平行层状云降水PS(parallel-stratiform)所占比例最少。(2)MCS多集中在6个区域发展,多在武陵山东南侧、大别山南坡、幕阜山北坡及江汉平原一带形成,由生成地向东或东偏南方向移动,部分准静止后向建立型BB(back building)类MCS从发生到消散基本维持在原地。(3)从月季变化来看,6月和7月引发极端强降水的MCS个例最多,4月和9月的个例数最少。(4)MCS的平均生命史为5~8 h,多发于下午至傍晚;夜间、午夜前后为成熟高峰期;极端降水多在夜间发生,松滋、天门和红安市为极端降水多发地。

Based on the new generation of weather radar data from April to September during 2008-2018,70 mesoscale convective systems(MCS)induced extreme precipitation in Hubei Province were selected to study their the spatial and temporal distribution characteristics of linear MCS mature stages.The results are as follows.(1)In five linear MCSs,the proportion of AS(adjacency stratiform cloud precipitation)is the highest,while leading stratiform(LS)and parallel stratiform(PS)(parallel stratiform)takes the least proportion.(2)MCSs are mainly concentrated in six regions,mostly in the south of Wuling,the south of Dabie Mountain,the north of Mufu mountain and Jianghan Plain.They move from the generating place to the east or the south by the east,Part of them are quasi static and backward to the established BB(back building).BB MCS basically remained in place from occurrence to dissipation.(3)From the perspective of monthly change,MCSs occurred the most in June and July,and MCS cases with extreme heavy rainfall in April and September occurred the least.(4)The average life history of an MCS was 5-8 hours,most of which occurred from afternoon to evening,and the peak of maturity was at around midnight.Most of the extreme precipitation occurs at night.Songzi,Tianmen and Hong'an are the places where the extreme precipitation occurs.