The Stability of a Stationary Rossby Wave in a Baroclinic Zonal Flow

Abstract The stability of a stationary baroclinic Rossby wave embedded in a baroclinic zonal flow is investigated in the framework of the two-layer model. This investigation is relevant to the question of mountain-induced cyclogenesis, where such flow configurations may exist on the lee side of the topography. It is found that when the amplitude of the stationary Rossby wave is sufficiently large a flow which is stable upstream may become unstable downstream. The influence of the baroclinic shear is to reduce the growth rate of the instability in comparison to the corresponding barotropic case. Nonetheless the growth rates obtained can he significantly larger than those obtained for a baroclinic parallel zonal flow, possessing the same baroclinicity.