Diagnostic Analyses and Application of the Moist Ageostrophic Vector Q

Considering the main thermal forcing factor,which is critical for the development of synoptic systems,the concept of the moist ageostrophic vector Q is introduced.A formula of the moist ageostrophic Q and the ageostrophic diabatic equation,in which the divergence of the moist ageostrophic Q is taken as a single forcing term,is derived.Meanwhile,the moist ageostrophic Q is applied to diagnose a torrential rain process in North China.The results suggest that the moist ageostrophic Q can clearly reveal the system development during the torrential rain process; the corresponding relationship between the divergence of the moist ageostrophic Q and the rainfall area is better than that of the vertical velocity (ω) and the divergence of the dry Q; the 6-h rainfall region can be correctly drawn according to the negative area of the divergence of the moist ageostrophic Q,and its precipitation is positively correlated to the magnitude of the divergence of the moist ageostrophic Q.The research provides valuable information for improving short-term weather forecast.