一次热带气旋环流暴雨与前期一般性降水环境场的对比分析

登陆的台风环流暴雨是沿海地区重要的暴雨类型之一，降雨量大，范围广，危害大。本文应用诊断分析的方法，以1999年8月11日发生在山东半岛中东部大范围暴雨过程为实例，就暴雨发生前一般性降水时的环境场与暴雨发生时的环境场做了对比分析。结果表明，暴雨发生时均比暴雨发生前一般性降水时：低空辐合和高空辐散增强，低层水汽能量辐合及对流不稳定性增大，低空垂直环流发展。以上因子导致积云对流的发展。在弱垂直切变环境下，通过第二类条件不稳定(CISK)机制，使热带风暴减弱成的低气压环流维持，并促使中低压发生变化，使暴雨云团西行增强，暴雨增幅。

A DIAGNOSTIC ANALYSIS OF THE ENVIRONMENT FIELDS ON A TORRENTAL RAIN OVER QINGDAO AREA

The environment fields during the torrential rain process are compared with the environment fields before the torrential rain process. The results show that the low level convergence and high divergence, and the low level moisture flux convergence, the low level vertical circulation and convective instability environment during the torrential rain process are all more sigificantly intensified than them before the torrential rain process. So that the cumulus sonvection develops. In the weak shear environment the condition instability of the second kind (CISK) mechanism causes the pressure decrease and the increase of cyclonic circulation. Finally, the above factors result in the occurrence and develoment of the torrential rain process.