2004年7月两次强对流天气过程的对比分析

Contrast Analysis of Two Severe Convective Weather Processes

对两次强对流天气过程的影响系统、物理量场和雷达回波特征等进行了对比分析。分析表明:两次强对流过程有许多相似之处,高、低空西南急流适宜配置而引起的高低层动力场的耦合是强对流发生的动力条件,强对流发生在低层露点锋区及低层水汽通量和散度辐合、高层则相应辐散的大值区域。高低层相对散度正值越大,其所产生的雨量也就越大。多普勒雷达反射率因子图上弓状回波的后侧出现下沉入流急流,相应速度图上的速度值越大,回波移动速度越快,预示着所造成的地面风力也就越大。

Two severe convective weather events are analyzed. The results show that this two events are similar in many aspects, Such as, the effect system, physical element fields and the radar echo features etc. The couple of the dynamic fields in upper and lower layers provides the dynamic condition. Convective weather occurred in the place of low-level front zone of clew point, and the place of convergence in the lower level and divergence in the upper level as well. The larger the difference between the convergence and divergence in upper and lower layers is, the heavier the rainfall is. The descending inflow jet appears at the back of the bow echo on the map of Doppler radar base reflectivity fields, the larger the corresponding radial velocity is, and the more rapid the movement of radar echoes is, the larger the wind on the ground is.