2013年巴彦淖尔市一次致灾冰雹天气的诊断分析

Diagnostic Analysis on a Disastrous Hail Weather in Bayannur in 2013

文章利用常规气象观测资料及新一代多普勒天气雷达资料,从大尺度环流背景、高低空急流的配置、局地气象条件和雷达回波的演变特征,对2013年7月21日发生在巴彦淖尔市的一次大范围冰雹天气过程进行了分析。结果表明:在亚欧大陆中高纬三槽两脊型环流背景下,高低空急流的配置为降雹提供了动力和热力条件,天气系统造成的系统性上升运动是冰雹发生的触发机制。不稳定能量、风的垂直切变、湿球温度0℃和-20℃层高度等环境场条件有利于雹暴的形成,深对流指数在冰雹发生前有明显增大的特征,风暴强度指数表明在热力学和动力学条件的共同作用下产生了此次冰雹天气。在强雷暴的发生过程中,雷达产品中最大反射率因子所在高度与单体质心高度、冰雹指数、VILmax值的"爆发式增长"和"爆发式降低"现象,对预警冰雹有很好的指示意义,高悬的强回波、多角形回波、速度图上的"大风区"和高的VILmax值等特征可作为冰雹预警的可靠信号。

Using conventional observation data and new generation Doppler radar data, this article analyzed a extensiveness hail weather process that occurred in Bayannur on July 21 from the aspects of large scale circulation background, high-low level jet con-figuration, local weather condition and the change characteristics of radar echo. The results showed that the high-low level jet config-uration offered power and heating condition in the circulation background of three troughs and two ridges in mid-high latitude, the system ascend motion that caused by weather system was the trigger mechanism of hail. The circulation condition of instability energy,wind vertical shear, wet bulb temperature, 0℃ and-20℃ height field was favourable of hailstorm forming,the deep convection index had obvious increscent feature in front of hail, windstorm intensity index indicated that the thermodynamics and kinetics condition produced this hail weather. In the process of powerful thunderstorm, the height of maximum reflectivity factor of radar products, height of center of mass, hail index, vertically integrated liquid water ＂explosive growth＂ and ＂explosive reducing＂ phenomenon of hail warn-ing had very good indicative significance, the uphang powerful echo, polygon echo, the gale area in hodograph, high VILmax value could regard as reliable signal of hail early warning.