A Modified Potential Vorticity Equation for Mesoscale Systems
适用于中尺度系统研究的位涡方程

A new set of atmospheric equations is derived in an adiabatic, and frictionless atmosphere, and the characteristics of the new equations are discussed. The new set of equations is useful in the evaluation of the potential effect of slantwise isentropic surfaces on the evolution of mesoscale systems since the potential temperature is included explicitly in the dynamic equations of the new set of equations. Further, by using the set of equations derived above, a modified potential vorticity equation more suitable for the study of mesoscale systems is developed, in which the term of divergence is involved explicitly on the right hand side. The new potential vorticity equation can be used in the study of the effect of divergence on the budget of potential vorticity and further in the discussion on the dynamic and thermodynamic processes of mesoscale systems.