Dispersion and angular analysis of acoustic modes in a shallow sea

An experiment that allowed constructing a pattern of mode signals radiated by a point source at the distances of 7 and 10 km has been staged in the Barents Sea. The image of mode signals focused by time reversal is obtained in the mode number-group delay coordinates. The used algorithm is based on the coincidence of frequency characteristics of modes of a real waveguide and an ideal waveguide in a shallow sea. A mechanism of the phenomenon that explains the observed results is proposed.