Quasi-geostrophic wave-CISK in an unbounded baroclinic shear

The basic state consists of a zonal flow, unbounded above and below, with constant vertical shear and Brunt-Vaisala frequency and zero meridional gradient of the potential vorticity; and convective heating is parameterized in terms of the convergence below an arbitrary level. The unstable waves in the free-shear problem grow rapidly and share many structural characteristics with dry baroclinic waves, although the dynamical process associated with dry baroclinic instability is absent; consideration of the potential vorticity dynamics of the unstable modes illustrates how heating may act as a dynamical surrogate for potential vorticity gradients. -from Authors