On the interactions between gravity waves and the diurnal propagating tide

The mutual interaction between a spectrum of gravity waves with phase speeds of 0, ±15, ± 30 m s-1, and the diurnal propagating tide is investigated. The tide is simulated by an equivalent gravity wave formalism on a rotating plane, and the interaction is accomplished through an iterative scheme wherein the momentum deposition and effective eddy diffusivity generated by the breaking gravity waves are treated through a simple parameterization. The gravity wave stress is shown to be an effective mechanism for damping the diurnal tide. In addition, the interaction is shown to produce local time variations in eddy diffusivity which may have important photochemical consequences, as well as momentum forcing of secondary semidiurnal and terdiurnal oscillations. A Rayleigh friction parameterization of the wave stress effect is derived with potential use in two- or three-dimensional numerical models of the diurnal atmospheric tide. © 1991.