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气象:2018,44(11):1404-1413
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2016年初冬陕西一次高架雷暴天气过程分析
郭大梅,章丽娜,王秀明,胡启元
(陕西省气象台,西安 710014; 中国气象局气象干部培训学院,北京 100081)
Analysis on Elevated Thunderstorm in Shaanxi in Early Winter of 2016
GUO Damei,ZHANG Lina,WANG Xiuming,HU Qiyuan
(Shaanxi Central Meteorological Observatory, Xi’an 710014; China Meteorological Administration Training Centre, Beijing 100081)
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投稿时间:2017-05-26    修订日期:2018-08-30
中文摘要: 利用常规地面高空观测资料、西安和安康多普勒天气雷达观测资料、欧洲中心细网格模式预报等资料对2016年11月22日发生在陕西地区的一次雷暴过程进行诊断分析,结果表明:陕西中南部雷暴区位于地面冷锋后350~500 km的区域内,雷暴区3 km以下是深厚的冷垫,同时中低层存在明显的逆温层,低层是绝对稳定的大气层结,这说明此次雷暴天气为高架雷暴。通过诊断饱和假相当位温、假相当位温、湿位涡和绝对涡度表明不同地区不稳定机制是不同的。西安地区不稳定机制为条件性对称不稳定,安康地区不稳定机制为条件性不稳定。在条件性对称不稳定区域,降雪回波呈现出数个平行带状回波,与0~6 km风切变矢量(西西南风)平行;在条件性不稳定区域,降水回波为小尺度的块状回波。强垂直风切变表明大气斜压性强,中高层暖湿气流增强了大气的湿斜压性,从而使中高层形成条件性对称不稳定,产生倾斜对流;中低层偏南气流输送暖平流和水汽,使得大气较为暖湿,中高层温度平流较弱,大气较干,形成位势不稳定,锋面抬升中低层暖湿大气使其饱和,位势不稳定转化为条件性不稳定,产生垂直对流。不稳定与上升运动及回波高度有着较好的对应关系。
Abstract:Based on conventional observation data, Xi’an and Ankang Doppler weather radar observation data and ECMWF numerical model data (0.25°×0.25°), an elevated thunderstorm process in Shaanxi in early winter of 2016 is analyzed. The results show that the thunderstorm area in the center and south of Shaanxi Province was located in the area of 350-500 km after surface cold front. Deep cold air cushion existed under 3 km in thunderstorm area. At the same time, there was temperature inversion in middle low level and absolute stability of atmospheric stratification in low level. All these make clear that the thunderstorm was an elevated one. Through analyzing moist potential vorticity, saturated pseudo equivalent potential temperature, pseudo equivalent potential temperature and absolute vorticity, we found that the unstable mechanism is different in different regions.Unstable mechanism for Xi’an Region is conditional symmetric instability while unstable mechanism for Ankang Region is conditional instability. In conditional symmetric instability area there are a number of parallel snowfall echoes, parallel with vertical wind shear vector from 0 to 6 km. In conditional instability area there are small scale echoes. The strong vertical wind shear indicates that the atmospheric baroclinic is strong. Warm moist air flows between middle high layers enhance atmospheric baroclinicity, thus producing conditional symmetric instability which results in slantwise updraft. Southerly airflow in the low middle level convey warm advections and water vapor which makes the atmosphere moister and warmer, making the atmosphere moister and warmer, but high level temperature advection is weak and the atmosphere is relativerly dry. So potential instability is formed. When the front surface uplift warm moist air makes it saturated, potential instability changes into conditional instability, resulting in vertical convection. Thus, there is a good correspondence between the instability and the ascending motion and the echo height.
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基金项目:国家自然科学基金项目(41475042)资助
引用文本:
郭大梅,章丽娜,王秀明,胡启元,2018.2016年初冬陕西一次高架雷暴天气过程分析[J].气象,44(11):1404-1413.
GUO Damei,ZHANG Lina,WANG Xiuming,HU Qiyuan,2018.Analysis on Elevated Thunderstorm in Shaanxi in Early Winter of 2016[J].Meteor Mon,44(11):1404-1413.