Physical modeling of sound propagation in the shelf zone of the oceans

The aim of the work was to study the vertical structure of short mode pulses near the critical thicknesses of waveguides of constant and variable depth with different bottom models. In the course of the work, the expression of the solvability criterion for short mode pulses in waveguides of constant depth with different types of bottom was theoretically obtained. A formula for the optimal resolution distance of successive mode pulses arriving at the signal receiving point, depending on the parameters of the emitted signal and the parameters of the waveguide itself, is obtained. Based on the theoretically obtained results, a mathematical model for the propagation of short mode pulses in waveguides of constant and variable depth has been developed. The theoretical model for calculating the envelope of an acoustic radio pulse in a waveguide of variable depth with various types of bottom is obtained. This model numerically describes the signal propagation, during which the emitted short signal is divided into pulses by individual modes, associated with intermode dispersion, and the pulse broadening at each mode due to the influence of intramode frequency dispersion. In the course of the experimental part of the work, the signal amplitude was measured over time on paths of various lengths with a fixed receiver depth, and the duration of the emitted signal at the receiver was also determined. The amplitude of the received sequential mode pulses was measured at various depths of the receiver.