2002年4月5日罕见的强对流天气成因及预报分析

对2002年4月5日发生的自1986年以来同期范围最大的一次强对流天气过程进行了较为深入的分析,得出此次强对流天气过程主要是以下因素影响造成的:(1)亚洲中低纬度地区短时期内出现异常强的经向环流,表现为高原低槽东移发展加深,诱发地面江淮气旋波强烈发展,引导地面冷空气从西路快速南下为强对流提供了动力抬升的重要条件;(2)低层流场上中尺度系统异常活跃,有发展强盛的SW急流扰动以及由西北气流与西南气流构成的冷式切变线,气流辐合作用明显;(3)大气中不稳定能量的积聚等。

Analysis for the Factors and Forecast of Severe Convection Weather on April 5th, 2002

Severe convection weather such as hail and lightning storm is the main disaster in Guangxi at spring. Studies on a great amount of examples indicate that severe convection was made directly by mesoscale and microscale system at the specific macroscale circulation. The severe convection that happened on April 5th 2002 was the largest scale at the same time in the past 18 years. By the thorough studies on this process, it must had been influenced with the main factors as follow: 1) In short term, abnormal strong meridional cell appear at middle and low latitude of Asia. High trough at low latitude moved to east and developed which placed a premium on the strong development of Jianghuai cyclone wave and steered surface cold air moving speedily to south area from west path. All of these positions offered the important conditions for dynamical lifting. 2) At streamline field of low level, mesoscale systems were active with strong developed southwest jet disturbance and cold shear line between northwest wind and southwest wind, and the convergence of stream was distinct. 3) The instability energy of atmosphere accumulated.