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

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.

Sea Level Fluctuations

“…Changes in the ocean level by various wave and non-wave processes, the action of typhoons and cyclones over the water area, and the presence of various currents directly affect the propagation of sound in the ocean [5,6]. On the other hand, solving the inverse problem, we can make hydroacoustics serve as a tool for studying various sea processes.…”

Effect of Subsurface Mediterranean Water Eddies on Sound Propagation Using ROMS Output and the Bellhop Model

“…The sound speed in the ocean is a function of three variables: temperature, salinity, and pressure (depth). The sound speed increases with the increase of any of the three parameters following the empirical formula presented below [26,[28][29][30].…”

Mesoscale Eddy Effects on Vertical Correlation of Sound Field and Array Gain Performance

“…Gao et al delved into the spatial correlation in warm and cold eddies, elucidating the correlation mechanism using ray theory [19]. While current research about the influence of eddies on sound propagation characteristics primarily concentrates on energy changes [20][21][22], there is an absence of comprehensive investigations into the spatial correlation of the sound field and its impact on the array gain.…”