The saturation of gravity waves in the middle atmosphere. Part I: critique of linear-instability theory

Abstract

Current theories assume that saturation results from linear instability: that the waves of the tail grow in amplitude with height (in response to the decrease of atmospheric density) until the system as a whole, or each portion of its tail, is rendered unstable. In the present paper the waves of the tail are recognized as being subject to a strong wave-wave interaction arising from the Eulerian advective nonlinearity - from the Doppler shifts that can be imposed upon them by the larger-scale winds of the wave system - a fact recognized in the corresponding oceanographic literature for about a decade now. -from Author