准地转Q矢量在河南省区域暴雨过程中的诊断应用

应用NCEP再分析资料及常规地面观测资料,对2005年7月21～24日河南省大暴雨过程中准地转Q矢量作了诊断分析,结果发现:在对流层低层850 hPa等压面上,Q矢量散度的负值区与暴雨落区有着较好的对应关系;Q矢量散度场在垂直方向上出现低层辐合、高层辐散配置时,利于暴雨的产生,暴雨区位于Q矢量辐合中心下方,降水的强弱与Q矢量的低层辐合及高层辐散强弱变化一致.Q矢量的y分量能较好地反映出锋生、锋消的作用,并能指示6～12 h后的暴雨落区.

A Diagnosis Quasi-geostrophic Q-vector Diagnosis of a Regional Heavy Rainfall in Henan Province

By using NCEP reanalysis data and some routine observation data, the quasi-geostrophic Q-vector of the regional heavy rainfall process in Henan province from 21 to 24 July 2005 was diagnosed. The results indicated that the negative area of the divergence field of the Q-vector was correlated well to the heavy rainfall regions at the 850hPa. It was easier for the heavy rainfall occurrence when the divergence field of the Q-vector appeared convergence at the low level and divergence at the high level on its vertical direction. The heavy rainfall regions were located under the convergence center of the Q-vector. The precipitation intensity coincided with the strength of convergence at the low level and divergence at the high level. The Q-vector y component reflected well the function of frontogenesis and frontolysis, and it indicated the location of the heavy rainfall from 6 to 12 hours in the future.