Based on the final analysis data of NCEP,the rainstorm occurred in Dengfeng on March 3,2007 is analyzed from the following aspects: dynamic and thermal energy conditions,water-vapor transportation,wet Q vector and so on.

A heavy rain process of the Changjiang-Huaihe Meiyu front (MYF) is diagnosed by the agency of the traditional Q vector partitioning (QVP) method to decompose the wet Q vector (Q) in a natural coordinate system that follows the isoentropes and by using the numerical simulation results of the revised MM4 meso-scale model.

With non-adiabatic latent heating completely considered and based on a primitive equation, derived are an expression of the modified wet Q vector (Q*)(hereafter termed QM) and a non-geostrophic ω equation wherein the QM divergence is taken as a forcing term with a diagnosis comparison of QM to Q* in the context of a Meiyu front synoptic process.

Based on the routine observations,an ageostrophic wet Q-vector diagnosis of a heavy rain process over the eastern Qinghai-Xizang Plateau during 18-19 July 2005 is made.

The ageostrophic wet Q-vector method is applied to diagnose a torrential rainfall process in Shandong Peninsula on August 1,2001,which is caused by a temperate cyclone transformed from typhoon "Toraji"moving northward.

The results show that, rain storm most likely occurs in a Q-vector convergent area and it locates near the ascending branch of a secondary circulation,which is triggered by ageostrophic wet Q-vector and also can benefit the maintenance and development of rainstorm.