Effects of horizontal non-uniform distribution of the upper-layer sound velocity profile on prediction of characteristics of deep-sea convergence zone

The weak change of the horizontal distribution of the sound velocity profile (SVP) in the deep-sea upper layer will affect the characteristics of the sound field convergence zone (CZ). A method for accurately predicting the characteristics of the deep-sea sound field CZ is proposed by analyzing the propagation track of the outgoing sound rays in the direction of 0°. This method only needs to consider the horizontal variation of the upper-layer SVP near the location of the sound source and CZ, which is helpful to reduce the measurement workload of horizontal non-uniform distribution of SVP in deep-sea sound propagation survey. The method is verified by simulating the horizontal non-uniform distribution of the SVP in the upper layer of the deep sea caused by small amplitude internal wave. The analysis results of the deep-sea measured data in the South China Sea also show that when the horizontal non-uniform distribution of the upper layer SVP is not considered, the location and energy distribution in the CZ predicted by the model is different from the measured results, and the difference has a distance accumulation effect. Because of this effect, the prediction error of the second CZ can reach 3 km. When considering the horizontal variation of the SVP within the CZ width, the characteristics of the CZ predicted by the model are in good agreement with the measured results, and the prediction error of the second CZ is less than 1 km.