Effect of the sound speed field inhomogeneities on the propagation over a continental slope

Results obtained by processing the data of an experiment on the propagation of explosion-generated sound signals from the deep ocean to the coastal wedge are presented. The propagation path, 275 km in length, passes areas with inhomogeneities of the sound speed field, including the front zone. The effects of these inhomogeneities on the sound field formation are analyzed for different parts of the path. The frequency band of the analysis covers 25-400 Hz. It is shown that after the path crosses the boundary of the front zone; the dispersion curves of the first and second modes nearly coincide. The signals of these modes are not resolved in time, and as the distance increases, they cause pronounced modulation of the level in the signal tail at low frequencies (25-50 Hz). Therefore, to separate the effect of sound interaction with the inclined bottom, i.e., the effect that determines the increase in the sound level over the coastal slope, it is necessary to perform a detailed analysis of the mode content of the received signals. (C) 2000 MAIK "Nauka/Interperiodica".