MESOSCALE INSTABILITY OF A BAROCLINIC BASIC FLOW——PART I: SYMMETRIC INSTABILITY

This is the first part of "Mesoscale Instability of a Baroclinic Basic Flow",which deals with the stability of a baroclinic flow against mesoscale perturbations parallel to it and the possibility for occurrence of a bandwise mesoscale disturbance along with its effects on triggering and organizing deep convections in a stratified atmosphere of weak static stability.The atmospheric perturbation equations with anelastic assumption are formed in the way that they are suitable to be solved by generalized matrix method and by shooting method.The mesoscaIe instability spectra and the structures of the characteristic perturbations are calculated for linear,hypertangent profiles and realistic wind profile sounded before a squall line event.By energy analysis the effects of baroclinity of the basic flow on generating such kind of ageostrophic inertial convection are also discussed.