Analysis of characteristics of the distance-arrival angle structure in the deep-sea convergence zone

The deep-sea convergence zones (CZs) of different orders exhibit strong similarities in their acoustic field characteristics. For distinguishing and detecting convergence zones, this study characterizes the distinctive features of different-order CZs through the distance-arrival angle structure of the vertical beam-domain acoustic field in deep sea. Based on ray theory, the vertical beam-domain acoustic field structure of deep-sea CZs is analyzed and the concept of a “horn-shaped” distribution pattern is proposed to describe their spatial characteristics. A quantitative metric is defined to measure the structural differences between CZs of varying orders. Both numerical simulations and experimental data demonstrate that the characteristic metric of the vertical beam-domain acoustic field decreases as the CZ order increases. The study reveals that under the condition of constant limiting ray angles, the increasing span difference between refracted rays with propagation distance serves as the primary mechanism for the observed reduction in the distance-arrival angle structural metric K with higher-order CZs.