Abstract:
In this work the opportunity to use range-frequency dependence of losses (RFDL) for restoration of the acoustic characteristics of the marine bottom is discussed. RFDL and dependence of optimum propagation frequency (OPF) (the frequency, at which losses are minimum) from a sound-speed profile, and characteristics of the layered bottom (impedance, attenuation of longitudinal and share waves in the bottom, sediment layers thickness) are analyzed. For numerical simulation of sound propagation in shallow water, a normal-mode method was used. Numerical simulation has shown that the optimum frequency of sound propagation in shallow water is rather sensitive to the acoustic characteristics of the upper sediment layers. In this work the opportunity to use RFDL and OPF for reconstruction of characteristics of the sea bottom and creation of acoustic model of the bottom in a wide range of frequencies is discussed. For experimental measurement of RFDL in shallow water, a method of broadband pulsing probing was used. The signal was received by autonomous bottom modules. The satisfactory agreement of experimental measurements with the results of numerical simulation confirms this opportunity of reconstruction of the bottom in shallow water by RFDL. [Work supported by RFFI Project N 96-02-18944.]