Geometrical-Acoustics Approximation in the Study of the Low-Frequency Pulse Propagation in a Near-Bottom Oceanic Waveguide

Abstract

We present the results of experimental studies of propagation of the low-frequency pulsed signals in the deep-water region of the Indian Ocean under conditions of a waveguide open from the bottom side when the signal from a near-surface source, which is received by the near-bottom receiver, is a sequence of reflections from the bottom and the ocean surface. The spatiotemporal diagram showing the amplitudes of the received pulses as functions of the distance and the relative time of their arrival is used for the data processing. It is shown that using a simple model of the stratified waveguide with a constant bottom and geometrical-optics approximation for calculating the tone-signal field, one can achieve good agreement between the experimental and theoretical results. In particular, this allows one to determine the effective waveguide depth for the frequency range 5–40 Hz and estimate the reflecting-boundary characteristics. The obtained results can also be used for predicting the parameters of the low-frequency signal propagating in the waveguides of this kind.