Analysis of the characteristics of the acoustic convergence zone in the northern south China sea

Abstract This study analyzed the convergence zone distance under the critical depth conditions of the sound source and the occurrence probability of the convergence zone at different sound source depths in the northern South China Sea by using the Bellhop model and GLORYS12V1 data. The results show that with the increase of water depth, the critical depth of the sound source decreases, and the corresponding convergence zone distance increases. Under the same water depth conditions, the convergence zone distance is closer in winter and farther in summer. When the water depth is less than 3000 meters, the seasonal variation of the convergence zone distance is relatively large, while when the water depth exceeds 3000 meters, the variation is relatively small. Except for the marginal areas, the occurrence probability of the convergence zone is above 99% in most sea areas throughout the year. The probability distribution in the marginal areas shows seasonal differences. With the increase of the sound source depth, the high-probability area expands from the deep water in the east to the northwest, and the low-probability area is concentrated in the marginal areas or the closed ring in the southwest corner. The range of the high-probability area is usually larger in winter and spring than in summer and autumn.