Application of the Convective Vorticity Vector to the Analysis of a Rainstorm
对流涡度矢量在暴雨诊断分析中的应用研究

Although potential vorticity is a common and useful physical quantity for meteorological analysis,it is a little weak in deep convective systems due to the apparent slant of moist isentropic surfaces.Therefore,convective vorticity vector(CVV) introduced by Gao et al.(2004) is used to study deep convective system.By using CVV,a heavy rainfall event that occurred in North China is investigated in this paper.The result shows that the vertical component of the CVV is a good indicator for convective rainstorm in the mid-latitudes and its high value region is highly correlated with cloud hydrometeors and rainfall.The rainstorm is located in the region where the vertical component of the CVV is large and to the north of its large gradient.The vertical component of the CVV is a cloud-linked parameter.Analysis of domain-averaged and mass-integrated quantities shows that the linear correlation coefficient between the vertical component of the CVV and the sum of mixing ratio of cloud hydrometeors is 0.92,which is larger than that between the moist potential vorticity and the sum of mixing ratio of cloud hydrometeors.The linear correlation coefficient between the vertical component of the CVV and precipitation rate is 0.71.The vertical component of the CVV represents the interaction between horizontal vorticity and horizontal equivalent potential temperature gradient,which can associate dynamic and thermodynamic processes with cloud microphysical processes.Thus it can help to understand the mechanism of convection development caused by the interaction between the circulation and clouds.Therefore,it can better trace the development and evolution of rainstorm systems.