The effect of the small-scale variability of sound velocity on the zonal structure of acoustic fields in oceanic waveguides
The article deals with the effect of the small-scale variability of sound velocity on the zonal structure of acoustic fields in oceanic waveguides. In the previously used analytical methods of calculation, the vertical distribution of the sound speed was described by the deterministic function which made it impossible to explain the discrepancy between numerical and field experiments. The present work is an attempt to determine the dynamics of the coordinate changes of the convergence zone boundaries depending on the level of the random component of the sound-speed field using the numerical method of stochastic modeling. Presented are the results of the numerical experiment on the propagation of sound in the Guiana region of the Atlantic Ocean carried out with the use of the radial programme of stochastic modelling. The results of the calculation were compared with the experimental data obtained earlier by N.N. Andreyev Acoustics Institute. In the numerical experiments the random component of the sound-speed field varied discretely. For each value of the random component of the sound-speed field we determined the coordinates of boundaries of the first convergence zone at the depths of reception of 190 m, 300 m and 400 m. At the same time, the boundary of the convergence zone which was closest to the source was decreasing, while the distant one was increasing. For fixed values of the random component of the sound velocity field the absolute displacement of the closest boundaries was less than that of the distant ones.