A theory of stationary long waves. Part III: quasi-normal modes in a singular waveguide.

Abstract

The paper deals with the fundamental issue of whether one can treat waves as normal modes when critical surfaces, where the phase speed of the wave matches the zonal wind speed, are present. In particular the question of whether a Rossby critical level (such as the zero-wind line for stationary waves) is absorbing or reflecting is raised and subsequently addressed. It is found that the critical level is never totally absorbing: Rossby waves are partially reflected even if the critical layer is dominated by dissipative processes. - from Author English