龙卷诱发原因的实例分析  

Analysis on the inducing cause of the tornado

作　　者：吴海英[1] 沈树勤[1] 蒋义芳[1] 王卫芳[1] 周其军[1] 

机构地区：[1]江苏省气象台,南京210008

出　　处：《气象科学》2009年第3期335-341,共7页Journal of the Meteorological Sciences

基　　金：江苏省科技厅项目(BS2006086)

摘　　要：利用雷达、自动站等资料,对一次龙卷过程进行了讨论与研究,详细分析了龙卷发生发展过程中系统结构及环境场特征的变化,并对龙卷的诱发原因进行了动力学探讨,结果表明:龙卷发生于气旋性涡度的高度集中区,对流层中层干冷空气的入侵,构成了上冷下暖的对流不稳定结构,当风场中的强风速带移近时,风速带上激发出中气旋系列,对流不稳定的加强,促使中气旋垂直对流强烈发展,从而导致龙卷天气的产生,进一步的动力学分析表明,当存在有较强的风垂直切变时,中尺度涡度方程中的倾斜项是造成中尺度扰动涡度变化的主要贡献者,也是这次龙卷天气产生的重要原因之一。With radar and automatic meteorological observing station data, a tornado course was studied. System structure during the development of tornado and the change of circumstance characters were analyzed in detail, and the inducing causes of the tornado course also were discussed dynamically in this paper. The results indicate that the tornado forms in highly converging area of cyclonic vortieity. Also dry and cold air invading from middle troposphere result in convective instability structure of cold advection at the upper level and the warm advection at the lower level. When strong wind band moved toward vorticity converging area, mesocyclone series is induced on the wind band. Strengthening of convective instability led to strong development of vertical convection in the mesocyclone, which results in the occur- rence of tornado. And further dynamical studies show that the inclination term of vorticity equation plays an important role in the variation of mesoscale disturbance vorticity and it is one of the important causes brought about tornado when there is stronger vertical wind shear in wind field.

关 键 词：龙卷 气旋性涡度 对流不稳定 

分 类 号：P445.1[天文地球—大气科学及气象学]