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 stabilityof a baroclinic flow against mesoscale perturbations parallel to it and the possibility for occurrence of abandwise mesoscale disturbance along with its effects on triggering and organizing deep convections in astratified atmosphere of weak static stability.The atmospheric perturbation equations with anelastic assumption are formed in the way that theyare suitable to be solved by generalized matrix method and by shooting method.The mesoscaIe instabilityspectra and the structures of the characteristic perturbations are calculated for linear,hypertangent profilesand realistic wind profile sounded before a squall line event.By energy analysis the effects of baroclinityof the basic flow on generating such kind of ageostrophic inertial convection are also discussed.