RESONANCE EFFECTS IN SOUND-SCATTERING BY INTERNAL WAVE-PACKETS IN A SHALLOW SEA

The influence of internal wave packets (IWP) on low-frequency sound pr opagation in a shallow sea (an oceanic shelf) is considered. On the ba sis of experimental data, a model of the IWP is developed. The model i s used in the theoretical analysis of sound scattering by the method o f interacting modes. In the framework of this approach, sound scatteri ng is found to be accompanied by both the energy transfer from the coh erent component to the incoherent (fluctuating) component of the sound field and the redistribution of the sound energy between the modes. I t is shown that the scattering of sound by IWP in a shallow sea leads to an increase of sound fluctuations and additional losses of the soun d energy. The frequency dependences of these acoustic effects (fluctua tions, additional losses) exhibit resonance features.