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

Abstract

Ocean processes can locally modify the upper ocean density structure, leading to an attenuation or a deflection of sound signals. Among these phenomena, eddies cause significant changes in acoustic properties of the ocean; this suggests a possible characterization of eddies via acoustics. Here, we investigate the propagation of sound signals in the Northeastern Atlantic Ocean in the presence of eddies of Mediterranean Water (Meddies). Relying on a high-resolution simulation of the Atlantic Ocean in which Meddies were identified and using the Bellhop acoustic model, we investigated the differences in sound propagation in the presence and absence of Meddies. Meddies create sound channels in which the signals travel with large acoustic energy. The transmission loss decreases to 80 or 90 dB; more signals reach the synthetic receivers. Outside of these channels, the sound signals are deflected from their normal paths. Using receivers at different locations, the acoustic impact of different Meddies, or of the same Meddy at different stages of its life, are characterized in terms of angular distributions of times of arrivals and of energy at reception. Determining the influence of Meddies on acoustic wave characteristics at reception is the first step to inverting the acoustic signals received and retrieving the Meddy hydrological characteristics.

Response of sound propagation characteristics to Luzon cold eddy coupled with tide in the Northern South China Sea

“…Moreover, the model effectively improves the low-frequency issues. Its advantages, including clear physical interpretation and rapid computation speed, have made it widely employed in range-dependent hydroacoustic propagation modeling (Zhang et al, 2011;Yang et al, 2016;Gul et al, 2017;Jiang et al, 2017;Cao et al, 2018;Li et al, 2018;Xiao et al, 2019;Hassantabar et al, 2021;Mahpeykar et al, 2022).…”

“…Regarding the influence of eddies on sound propagation, Ruan et al (2019) utilized the FOR3D model to investigate the impact of a cold eddy in the Luzon Strait on the convergence zone of the sound field based on the 3-D temperature and salinity fields output from the HYCOM model. Hassantabar et al (2021) used high-resolution ROMS and the BELLHOP model to discuss the effect on sound propagation by Mediterranean eddies during different periods. As for the influence of internal tidal waves on sound propagation, studies based on numerical simulation results appear to be more comprehensive and specific compared to theoretical model results.…”

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.…”

Hydroacoustics in Marine, Transitional and Freshwaters

“…In this Special Issue, the published papers were mainly related to applications of hydroacoustics in fisheries research and aquatic ecology, with some also addressing technical problems and monitoring. Papers related to fisheries acoustics dominated the submissions and covered all types of aquatic environments: rivers (Yangtze River [1][2][3], Pearl River [4], and River Thames [5]), lagoon channels (Ingril and Prévost channels [6]), natural lakes (Lake Poyang [3], Lake Stechlin [7], and Lake Dejguny [8]), artificial reservoirs (Three Gorges Reservoir [1,2]), and the sea (Mediterranean Sea [9], and South China Sea [10]). Three of the papers were related to the Yangtze River basin.…”

“…Two of the papers focused on the application of hydroacoustics in the marine environment. The paper by Bozroudi et al [9] "Effect of Subsurface Mediterranean Water Eddies on Sound Propagation Using ROMS Output and the Bellhop Model" was related to ocean dynamics and the characteristics of its processes using acoustic wave propagation. It concentrated on the influence of subsurface oceanic eddies on sound propagation.…”