Influence of tropical dipole in the East Indian Ocean on acoustic convergence region

The physical ocean phenomena in the affect changes of water body, which has an important influence on sound propagation. A hyperbolic frequency modulation (HFM) signal propagation experiment towed source East Indian Ocean (EIO) was conducted summer 2019. center is 300 Hz, and hydrophone receives data from 4130 m far. This first time that we have underwater acoustic survey Ocean. phenomenon—Indian Dipole (IOD) observed. experimental IOD are processed analyzed, effects depth fluctuation deep-sea convergence zone (CZ) formation mechanism phenomenon explained theoretically. results show second CZ not formed under warm mass by incomplete deep channel environment EIO. Owing to depth, disappears at distance where it should appeared. When becomes deeper, easier form CZ. Under IOD, thermocline location third It found shifts 2–3 km toward experiment. research significance guiding applications detection communication sonar complex environment.