ИСТИНА

Sound propagation in Arctic-like waveguides (regions with a strong interaction of the acoustic field propagating in the water layer with both ice cover and the bottom) is complex phenomenon. The authors have performed more than two dozen experiments in different seasons on the shelf of the White Sea and in Moscow region both in the active regime and in the noise interferometry regime. In the active regime, it was demonstrated that the presence of ice leads to a decrease in the critical frequencies of the modes. If the bottom gives off gas, its accumulation under the ice layer significantly affects the boundary conditions. Flexural waves propagate over the ice and can radiate energy into the water layer. Interference occurs and is significant, especially near and below the cutoff frequency of the waveguide. Ice movement causes crackling. Using the acoustic noise caused by the crackling as a signal (noise interferometry regime) on the Arctic shelf allowed to solve the inverse problem and to reconstruct the sea parameters, for example, tidal activity. Using several horizontally spaced hydrophones, it was possible to study the processes of the propagation of individual cracks in the ice.