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气象:2019,45(1):50-60
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一次夏季冷锋后暴雨的形成机制探析
李瑞萍,王秀明,夏扬,周晋红
(山西省太原市气象局,太原 030082;中国气象局气象干部培训学院,北京 100081)
Study on Formation Mechanism of a Summer Cold Sector Torrential Rainfall
LI Ruiping,WANG Xiuming,XIA Yang,ZHOU Jinhong
(Taiyuan Meteorological Service of Shanxi Province, Taiyuan 030082;China Meteorological Administration Training Centre, Beijing 100081)
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投稿时间:2017-09-30    修订日期:2018-09-12
中文摘要: 利用常规观测资料,卫星、雷达及NCEP再分析资料,对2013年7月9日山西太原至河北石家庄一带的暴雨成因分析表明:(1)山西太原附近的暴雨发生在持续性层云弱降水持续6 h之后,层云中镶嵌积云并伴有弱雷电活动,暴雨区位于地面冷锋北侧低层冷区中,距离地面锋面120 km以上,极易漏报;(2)850 hPa东北风显著增强,低层假相当位温小的干冷空气随东北风向西南方向伸展,低层稳定层持续增厚,不稳定区位于稳定的边界层之上,强降水由高架对流造成;低层东北风和高层西南风同时增强,锋区斜压性显著增强,锋面抬升加强,锋面抬升和与500 hPa西南气流相伴的干平流使得锋区上空大气层结由近中性的绝对稳定转化为位势不稳定,锋区抬升使得位势不稳定转化为条件性不稳定;(3)午后河北中西部大气层结绝对稳定,石家庄雷达监测到其附近数条平行于热成风方向的水平尺度几十千米的对流云带是由条件性对称不稳定导致的倾斜对流。
Abstract:By using conventional meteorological data, satellite data, radar data and NCEP reanalysis data, the instability formation process of a torrential rainfall from Taiyuan to Shijiazhuang on 9 July 2013 is stu died. The results show that the torrential rainfall near Taiyuan occurred after light stratiform precipitation existed for six hours. The convective precipitation with weak thunder and lightning was embedded in the stratiform and it was located behind the cold front, more than 120 km away from surface front. Such cold sector torrential rainfall is easy to be missed. From 08:00 BT to 14:00 BT, depth of planetary boundary layer (PBL) cold air was continuously deepening, the dry and cold air mass with low pseudo equivalent potential temperature extended from northeast to southwest, and the unstable atmosphere was situated over the stable boundary layer, so the torrential rain was caused by elevated convection. The northeast wind at 850 hPa and the southwest wind at 500 hPa were strengthened at the same time, baroclinicity of frontal zone got stronger, the atmospheric stratification was transformed from absolute stability, which was almost neutral, to potential instability by the dry advection in 400-500 hPa and was moistened at lower level by frontal lifting. The potential unstable layer changed to conditional unstable layer by the frontal lifting of warm and humid air layer. In the afternoon, the atmosphere was absolutely stable near Shijiazhuang.
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基金项目:国家自然科学基金项目(41475042)、公益性行业(气象)科研专项(GYHY201506006)和中国气象局预报员专项(CMAYBY2017 092)共同资助
引用文本:
李瑞萍,王秀明,夏扬,周晋红,2019.一次夏季冷锋后暴雨的形成机制探析[J].气象,45(1):50-60.
LI Ruiping,WANG Xiuming,XIA Yang,ZHOU Jinhong,2019.Study on Formation Mechanism of a Summer Cold Sector Torrential Rainfall[J].Meteor Mon,45(1):50-60.