摘要
2012年8月4日夜里到5日,受台风倒槽影响,豫西出现一次罕见的大暴雨天气过程,暴雨中心嵩县日降雨量达196.6 mm,仅次于历史极值(264.7 mm)。为深入研究豫西地区台风倒槽大暴雨的形成机理,提高对此类天气的预报能力,依据河南省地面常规气象观测资料、降水资料,利用NCEP(1°×1°)再分析资料、FY2D卫星云图资料、FY2E卫星TBB资料、洛阳市新一代多普勒雷达等资料,对此次大暴雨过程产生的环境条件和触发机制进行了诊断分析。结果表明:1)此次大暴雨事件主要是由随高度西倾的台风倒槽、700 hPa干线及925 hPa偏东北气流与台风“苏拉”减弱后的热带低压后部东南气流共同作用所致。2)低层对流不稳定,中高层有弱的干冷空气侵入,为大暴雨的产生提供了有利环境条件;925 hPa中尺度辐合线及地面冷空气为台风倒槽中形成暴雨提供了启动条件。3)台风倒槽云系中,有多个中尺度对流云团生成并组织化持续影响,是导致这次局地大暴雨的主要原因,同时地形对降雨量有一定增幅作用。4)对流参数中的对流有效位能(CAPE)、K指数、Li抬升指数在暴雨发生前后有明显的拐点,对大暴雨的预报有很好的指示意义。
From the night of August 4 to 5,2012,under the influence of typhoon trough,a rare severe rainstorm occurred in western Henan.The daily rainfall in Songxian county,the center of the rainstorm,reached 196.6 mm,second only to the historical extreme value(264.7 mm).In order to study the formation mechanism of the severe rainstorm associated with typhoon inverted trough in depth and improve the forecasting ability of this kind of weather,the ambient conditions and triggering mechanism of this severe rainstorm process are diagnostically analyzed based on the precipitation data provided by the ground routine weather observation of Henan province,NCEP 1°×1°reanalysis data,FY2D satellite cloud photograph,FY2E satellite TBB data and the Luoyang Doppler Radar data.The results show that:1)This severe rainstorm event was mainly caused by the combined actions of the typhoon inverted trough tilting to the west with height,the 700 hPa dry line,the 925 hPa northeast airflow,and the southeast airflow behind the tropical depression caused by the weakening of typhoon“Sula”.2)The convective instability in the low layer and the invasion of weak,dry and cold air in the middle and high layers provided favorable ambient conditions for the occurrence of severe rainstorm.The mesoscale convergence line at 925 hPa and the cold air on the surface provided the start-up conditions for the formation of rainstorm in the typhoon inverted trough.3)In the typhoon inverted trough cloud system,a number of mesoscale convective cloud clusters were generated and systematically played continuous roles,which was the main cause for this localized severe rainfall.Meanwhile,terrain had a certain enhancing effect on rainfall.4)The convective parameters such as convective available potential energy(CAPE),K index and Li Lifting Index had obvious inflection points before and after the occurrence of the severe rainstorm,which are good indicators for the prediction of rainstorm.
作者
陈红霞
付伟基
李振锋
Chen Hongxia;Fu Weiji;Li Zhenfeng(Luoyang Meteorological Office,Luoyang 471000,China;Meteorological Observatory of Unit No.96606 of PLA,Luoyang 471000,China;Luoyang Electronic Equipment Test Center of China,Luoyang 471001,China)
出处
《气象与环境科学》
2020年第3期101-108,共8页
Meteorological and Environmental Sciences
基金
中国气象局·河南省农业气象保障与应用技术重点实验室基金项目(KZ201701h,KM202002)。
关键词
台风倒槽
大暴雨
环境条件
中尺度辐合线
typhoon inverted trough
severe rainstorm
ambient condition
mesoscale convergence line
