Eddy Heat Fluxes and Stability of Planetary Waves. Part II

Abstract

The stability analysis of baroclinic Rossby waves in a zonal shear flow examined in Part I is applied to the atmosphere. The basic state consists of a planetary-scale (wavenumber 1) Rossby wave in a zonal flow with vertical shear close to the minimum critical shear of the two-level model. The most unstable mode grows at the baroclinic time scale and is almost stationary relative to the basic wave. Maximum perturbation amplitude is at wavenumber 3, intermediate between the response scales of the two destabilizing mechanisms?vertical shears of the zonal flow and basic wave. The perturbation meridional scale is close to the radius of deformation. Applications to planetary-scale waves that transport heat are considered.