High frequency quasi-normal waves for nonstationary near-surface waveguide

The propagation of nonharmonic acoustic waves in an ocean refractive waveguide with slowly varying properties in horizontal directions and time is discussed. The waveguide is modulated as a water layer with plane boundaries. The wavelength is assumed to be small in comparison with the width of the layer. A set of asymptotic solutions of the wave equation called as quasi-normal waves and nonstationary eikonal equation are constructed.