Theoretical Analysis of the Influence of Weakly Divergent Beams on the Formation of the Spatiotemporal Structure of Pulse Signals in the Sea of Japan

Abstract

Using numerical modeling based on mode theory and the geometric-acoustic approximation, it was determined that in addition to classical quadruples of pulses present in the spatiotemporal field structure, the emergence of additional signals with relatively short delays is caused by the formation of weakly divergent multimode beams in the underwater sound channel of the Sea of Japan; these modes correspond to smooth extrema in the dependences of the spatial interference period of neighboring modes and their group velocity on the mode number. For one of the two sound speed profiles typical of the Sea of Japan, it was shown that at relatively high frequencies, it is possible to receive two groups of additional signals: weakly divergent beams formed by relatively low- and high-order modes.