Analysis of underwater acoustic propagation characteristics of coral reef slope topography

Based on the analysis of acoustic signal attenuation and terrain blocking effect under the condition of island and reef slope terrain, the distribution of underwater acoustic field and its effect on sound propagation are studied. A multi-path acoustic channel model is established by using the theory of acoustic model combining the measured topography and hydrological data. In addition, based on the Bellhop and RAM acoustic simulation method, the sound field characteristics of different terrains, such as sound rays traces, sound transmission loss and signal delay, are simulated, and the distribution characteristics of sound field under the condition of island and reef slope terrains are obtained. The results show that: (1) The slope topography of the reef is the key factor that affects the acoustic propagation modes; (2) The target in the shallow water area on the outer edge of the slope is not easy to be detected by the sonar at the top of the reef slope; (3) The steep slope terrain is good for the sound propagation of the sound source in shallow water, however, when the sound source depth is large enough, the gentle slope terrain is more conducive to sound propagation, and the number of eigenrays in the gentle slope terrain can reach 5 times of that in the steep slope terrain. The research results can provide theoretical basis and technical reference for the characteristic analysis of underwater acoustic field and the underwater acoustic countermeasure in island and reef areas.