The influence of internal waves on losses during sound propagation on a shelf

We discuss the results of investigations into the influence of internal waves on sound losses during propagation along stationary lanes on shelves of the Sea of Japan and the Sea of Okhotsk. Measurements were conducted with a Mollusk-07 autonomous vertical acoustic-hydrophysical measuring system and TONE-320 and FM-290–330 autonomous electromagnetic-type emitters generating a tonal acoustic signal and a frequency modulated signal, respectively. It is established that sound losses at 290–330 Hz as a result of internal waves do not exceed 5 dB. At the same time, intensive nonlinear internal wave packets that are relatively rare but characteristic of a shelf can increase losses up to 15 dB.