2006年陕西两次强对流冰雹天气过程的对比分析

Comparative Analyses on Two Severe Convective Hailstorm Weather Processes in Shaanxi Province in 2006

利用TBB资料、NCEP再分析资料、自动气象站资料及多普勒雷达等多种资料,对比分析了2006年初夏和盛夏两次强对流冰雹天气过程的环境场条件和中尺度系统的演变。结果表明,强的不稳定层结和一定的外部抬升力条件是产生强对流天气的共同物理量特征;高层暖、中层冷、低层暖的三层温度平流中心所叠置的区域与降雹区有较好的对应关系,对流层低层的逆温层(干暖盖)更有利于深厚对流活动的产生;适宜的0℃层和-20℃层高度有利于雹粒的增长。流场的尺度分离能够分辨出产生强对流冰雹天气的中尺度系统;地面能量场上表现有中尺度的Ω系统。初夏过程以冰雹、强风为主,盛夏过程冰雹、强降水比较突出;移速快、膨胀迅速的云团易产生冰雹和强风,而移速缓慢、对流合并显著的云团易出现强降水和冰雹。强回波伸展高度越高,入流显著、上升气流强盛的对流系统产生的天气愈剧烈,愈易出现大冰雹。

Using the TBB,NCEP reanalysis,automatic weather station and Doppler radar data and etc,the environmental physical field and mesoscale characteristics of two severe hailstorms in early summer and midsummer of 2006 are analyzed,as well as similar and different characteristics in two hailstorm processes are found.Similar physical characteristics of two processes producing severe convection weather are strong unstable stratification and certain external uplift condition.Overlay among warm advection on the upper and lower levels,respectively,cold advection on middle level of troposphere has a good correspondence with the falling area of hail,and inversion layer on lower level of stratification makes for producing deep convection.Moreover,the suitable 0℃ and-20℃ layer thickness is favorable for hail pellet increasing.Mesoscale system producing severe convection can be clearly seen from the stream field after filtering,and there exists a mesoscale Ω-shape system in the surface energy field.Hailstorm and strong wind are the main in early summer,but the hail and severe precipitation are ones in midsummer.The hail and strong wind are often produced in cloud cluster that rapidly move and expand,hail and severe precipitation are appeared in the cloud cluster that slowly move and markedly combine.The higher the height of severe echo extend,convension system of significant inflow and strong updraft produce more severe weather,the easier the big hail present.