Baroclinic Instability in a Fluid with Three Layers

Abstract

A three-layer model is used to study the effect of curvature in the vertical profile of the horizontal velocity on the linear baroclinic instability of a simple quasi-geostrophic flow. Potential vorticity is conserved and the ?-effect is included. The results indicate that the range of unstable wavelengths increases as the curvature is increased from zero. For a given physical state, there may be more than one critical wavelength for which the waves are marginally stable. Growth rates for ? = 0 and the structure of the fastest growing waves are given. A comparison is made between two-layer, three-layer and continuous systems.