Abstract
The energy analysis of the two-layer frontal model of Kotchin (1932) and Orlanski (1968) is reformulated. The new formulation is based on separating the contributions to the eddy kinetic energy of the unstable waves by the changes in 1) the difference in relative momentum between the layers (multiplied by the shear), and in 2) the available potential energy. Such a separation results in a clear characterization of the instabilities, particularly near the Rayleigh, Helmholtz and baroclinic instability limits. The mean meridional circulation induced by the unstable waves is analyzed.
