2005年汉中市秋季连阴雨的若干特征

利用常规观测资料,对2005年8月15日～16日山西省忻州市局部及中南部分地区强暴雨云团发生发展条件进行了诊断分析。结果表明,稳定少动的副高北侧大尺度冷湿云带前沿易产生中低涡,中低层Q向量辐合使局地次级环流加强,有利于不稳定能量聚积,形成中尺度能量系统,为对流云团发生发展奠定了基础;ST与K指数强度变化伴随强对流云团发生发展过程,并具有明显的中尺度特征及先兆作用;中低层冷湿气流的入侵是触发不稳定能量释放的重要条件。

The Condition of Occurrence and Development for the Sharp Heavy Rainstorm Cloud Cluster Happened on 16th August

Based on the routine observed data, the occurrence and development of the sharp heavy rainstorm cloud cluster is diagnosed. The results show that the vortex easily happens at the front of the large-scale steady cold and moist cloud belt on the north of the subtropical high. And the convergence of Q vector over low-mid level strengthens the sub-circulation and it helps the accumulation of instability energy, therefore the mesoscale energy system which is the basis of the occurrence and development for convective cloud cluster is established. The occurrence and development of the convective cloud cluster is accomplished by the strength variation of the ST and K indexes. At the same time, it shows the obvious mesoscale characteristics and precondition effect and the entrance of the cold and moist flow over low-mid level is an important condition of the release for instability energy.