Analysis of Underwater Acoustic Propagation under the Influence of Mesoscale Ocean Vortices

Sartaj Khan,Yang Song,Shengchun Piao,Jian Huang

doi:10.3390/jmse9080799

Abstract

Mesoscale ocean vortices are common phenomenon and fairly distributed over the global oceans. In this study, mesoscale vortex in the South China Sea is identified by processing of AIPOcean data. The characteristic parameters of the identified vortex are extracted by using Okubo-Weiss (OW) method. The empirical sound velocity formula and interpolation method are used to obtain the spatial characteristics of temperature and sound velocity of the mesoscale vortex. After this, a theoretical model based on the Gaussian method is established to fit and simulate the vortex parameters. Using this model, the influence of mesoscale vortex strength, cold and warm vortex, vortex center position and sound source frequency on sound propagation are analyzed in COMSOL software. Finally, the actual parameters of the identified vortex are compared with the ideal Gaussian vortex model. It is found that different types of mesoscale vortices have different effects on the underwater sound propagation characteristics. Cold vortices, for example, cause the sound energy convergence zone to move toward the sound source, reducing the convergence zone’s span, whereas warm vortices cause the sound energy convergence zone to move away from the sound source, increasing the convergence zone’s span. Furthermore, the stronger the mesoscale vortices, the greater the impact on the sound field. Our COMSOL-based results are consistent with previous research, indicating that this model could be useful for studying underwater acoustic propagation in vortices.

Highlights

IntroductionMesoscale ocean vortices (named eddies) are common and fairly distributed over the global oceans
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Based where η = 2 *( z − z 0)/ B, z is depth, z0 is the minimum depth of the sound velocity on the mesoscale vortex model established in Section 2, we choose 5 vortices with varying model and taken

Summary

Introduction

Mesoscale ocean vortices (named eddies) are common and fairly distributed over the global oceans They usually existing for 10 to 100 days and have medium spatial scales in the horizontal direction ranging from 50 to 500 km [4,5,6]. These kinds of vortices are widely distributed in the South China Sea. Earlier, Li et al [7] reported an anticyclonic ring detached from Kuroshio in the South China Sea. Using observation data, Wu et al [8] analyzed sound speed field in the same region of Ref. Wu et al [8] analyzed sound speed field in the same region of Ref. [7] by using

Methods

Results

Conclusion