On the Amplitudes Reached by Baroclinically Unstable Disturbances

Abstract

The maximum eddy energies reached by baroclinically unstable disturbances in some simplified numerical models (Gall, 1976b; Simmons and Hoskins, 1978) are compared to a scale-dependent measure of the energy available to the disturbances. It is found that, except for the longest wavelengths, the ratio of the maximum eddy energies to this available energy (the eddy efficiency) tends to remain constant relative to the large variations in the maximum energies. The roles of the growth rate of the initial disturbance and the ?-effect are discussed with reference to results from a maximally simplified model. It is shown that dimensional arguments paralleling Charney (1971) lead to the maximum energy versus scale relationships found in the numerical results.