强降水过程中垂直螺旋度和散度通量及其拓展形式的诊断分析

在垂直螺旋度的基础上，定义了散度通量，水汽垂直螺旋度和水汽散度通量三个宏观物理量.针对两次强降水过程，利用NCEP/NCAR实时分析资料对这些物理量进行诊断分析，结果表明，这些物理量能够比较准确地综合表征强降水系统所共有的典型动力场垂直结构，进而与降水系统的发展演变密切相关.这些物理量垂直积分的异常值区与观测的6 h累积地面降水具有良好的对应关系，表明它们对强降水的落区和降水系统的发展移动具有良好的指示预测意义.NCEP-GFS每日四次6 h预报场资料的计算表明，垂直螺旋度和散度通量及其拓展形式（水汽垂直 关键词： 垂直螺旋度 散度通量 水汽垂直螺旋度 水汽散度通量

Diagnosis of vertical helicity, divergence flux and their extensions in heavy-rainfall events

On the basis of vertical helicity, we define three parameters, namely, the divergence flux, moisture vertical helicity and moisture divergence flux. The parameters are calculated with NCEP/NCAR real analysis data in the two heavy-rainfall events occurring in China. The result shows that the parameters are closely related to the precipitation systems since they are capable of describing the typical vertical structure of dynamical and moisture fields. The anomalies of the parameters vertically integrated well correspond with the observed 6h-accumulated surface rainfall. This suggests that the parameters are capable of predicting and indicating the development and propagation of precipitation systems. The calculation with the 6-hour forecasting data of NCEP-GFS shows that the parameters have the ability of predicting precipitation and the moisture divergence flux is significantly beller than the other parameters in predicting precipitation.