一次飑线过程中龙卷及飑锋生成的中尺度分析

A MesoScale Analysis of Tornado and Squall Front Formingin a Squall Line Process

对１９８３年９月４日发生在陕西中部一次灾害性强风暴过程的天气形势、雷达回波、卫星云图、地面中尺度风场资料及灾情进行了综合分析研究，结果表明：此次灾害性强风暴是一次龙卷过程；龙卷出现在冷锋飑线带状回波尾部，呈典型的弓状回波（环状回波）；在卫星云图上表现为南北云系交绥处发展旺盛的中尺度涡旋云团，呈新月状；龙卷发生在地面“人”字形辐合线交点后部强西北风中；龙卷是由地面两条冷锋的共同作用造成的；飑锋回波出现在龙卷雷暴后部，表现为两条平行的线状回波，与经典理论有不同之处。

Comprehensive analyses and researches on synoptic situation, radar echo, satellite cloud picture, mesoscale surface wind field and disasters were carried out for a disastrous strong thunderstorm at midpart of Shaanxi Province on September 4, 1983. Results show that this disastrous strong thunderstorm yielded an tornado, appearing at the end of band echo of squall line which was a typical arched echo (cellular echo), on satellite cloud picture, a mesoscale vigorously developed turbulent cloud cluster was seen at cross point of herringbone cloud systems. The tornado took place in strong northwestern wind of rear part at cross of ground convergence lines, caused by mutual effects of two cold fronts on ground. The echo of squall front with two parallel bands appeared at the rear of the thunderstorm. This is different from the theory of squall front. 