Long-range reverberation in a randomly inhomogeneous shallow water with the use of focused radiation

The low-frequency bottom reverberation in a randomly inhomogeneous shallow water is investigated within the framework of a numerical experiment using vertical transmitting arrays focusing the acoustic field at various distances from the sea bottom. It is assumed that the main source of sound velocity fluctuations in the medium is represented by background internal waves. To focus the field, a phase conjugation of acoustic waves from a probe source positioned at the focusing point is used. It is demonstrated that the reverberation level is mainly determined by the presence of internal waves and may vary by 5–20 dB as the distance from the focusing point to the sea bottom increases up to H/2, where H is the channel depth.