Stability of a two-layer fluid model to nongeostrophic disturbances

Abstract

Sufficient conditions for stability of a linear inviscid two-layer model to nongeostrophic disturbances are derived. A bound on the growth rate of an unstable disturbance is also found. When the Rossby number R₀<1, these conditions reduce to the results established by Pedlosky (1964) within the confines of quasi-geostrophic theory. The present analysis provides a theoretical framework for further investigations of fluid systems characterized by strong concentrations of horizontal momentum, such that R₀ ?0(1). Application to atmospheric jet streams and the Gulf Stream, for example, is suggested by observationally established characteristics of these flow regimes.DOI: 10.1111/j.2153-3490.1973.tb01590.x