Effects of mesoscale eddies on the spatial coherence of a middle range sound field in deep water

Gao, Fei; Xu, Fanghua; Li, Zhenglin

doi:10.1088/1674-1056/ac6014

Cited by 3 publications

(3 citation statements)

References 20 publications

(26 reference statements)

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“…In the last decade, ocean-acoustic remote sensing has been trying to use acoustic models to better analyze the effects of mesoscale eddies on acoustic propagation, and the most common models usually include simple normal wave models [7], parabolic equation models [8], fast field models [9], ray models [10], etc. These models are based on a certain simplification of the actual problem and are obtained by making a reasonable approximation to the solution of the fluctuation equations.…”

Section: Introductionmentioning

confidence: 99%

A FEM Flow Impact Acoustic Model Applied to Rapid Computation of Ocean-Acoustic Remote Sensing in Mesoscale Eddy Seas

Liu,

Xu,

Jin

et al. 2024

Remote Sensing

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Mesoscale eddies have an impact on the marine environment mainly in two areas, namely, currents and changes in the sound velocity gradient due to temperature and salt stirring. The traditional underwater-related remote sensing acoustic remote sensing model is capable of analyzing the acoustic field under the change in sound velocity gradient, but it is not capable of analyzing the acoustic field under the influence of ocean currents. In order to more effectively analyze the changes in the acoustic field caused by mesoscale eddies, this paper proposes a FEM flow impact model applied to the rapid computation of acoustic remote sensing of mesoscale eddies in the sea area. The algorithm first performs a grid optimization of the sea area model based on vertical sound velocity variations and completes the classification of sound velocity layer junctions. At the same time, we construct the sound velocity gradient environment affected by the mesoscale eddy and then simplify the fluid flow in the mesoscale eddy into a non-viscous and non-rotating velocity potential, and then participate in the solution of the three-dimensional spatial fluctuation equations in the form of time-harmonic in the frequency domain, from which we can obtain the truncated sound pressure as well as the propagation loss, and quickly and completely characterize the acoustic remote sensing of the sea area of the mesoscale eddy. The paper verifies the effectiveness of the algorithm through SW06-contained flow experiments and further proposes an optimization formula for sound velocity inversion. We analyze this using measured data of mesoscale eddy fields in the Bering Sea waters during 2022 and find that eddies have a greater effect on the propagation of the acoustic field along their flow direction.

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Section: Introductionmentioning

confidence: 99%

A FEM Flow Impact Acoustic Model Applied to Rapid Computation of Ocean-Acoustic Remote Sensing in Mesoscale Eddy Seas

Liu,

Xu,

Jin

et al. 2024

Remote Sensing

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“…Xiao et al [18] focused on the influence of warm eddies in the Gulf of Mexico on sound propagation, observing the alteration in sound propagation paths, the expansion of convergence zones (CZs), and the dispersion of energy. 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.…”

Section: Introductionmentioning

confidence: 99%

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

Wu,

Qin,

et al. 2024

Remote Sensing

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To solve the problem of array detection performance in environments with mesoscale eddies, this study utilizes the Gaussian eddy model to describe the sound speed structure disturbed by eddies. Through numerical simulations, the corresponding sound field is obtained, and the transmission loss influenced by the eddy is analyzed. Furthermore, to investigate the relation between the array gain and spatial correlation in the eddy environments, the differences in vertical correlation at different positions and their effects on the vertical array gain of conventional beamforming (CBF) are studied. When the source is around the eddy center, the conclusions drawn are as follows: (1) The presence of an eddy changes the turning-point depth and the sound field distribution, significantly affecting the direct sound region and the first convergence zone, while having a minor impact on the first shadow zone. (2) In different eddy-induced environments, the first convergence zone maintains a high vertical correlation, but the vertical correlation of the direct sound region is greatly influenced by the eddy. (3) The array gain of CBF is consistent with the vertical correlation. When the correlation between each element of the sound field is great, the array gain increases with the number of array elements.

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“…Liu et al (2021a) analyzed a cyclonic eddy that was found in the Pacific Northwest to investigate the effect of eddy on the coupling coefficient of various orders of normal modes. Gao et al (2022) investigated the effects of the eddy on horizontal and vertical spatial coherence in deep water with the Gaussian eddy model presented by Calado et al (2006). However, due to the movements of eddies, their corresponding acoustics observation data need to be measured through specialized design experiments.…”

Section: Introductionmentioning

confidence: 99%

Observation of a mesoscale warm eddy impacts acoustic propagation in the slope of the South China Sea

et al. 2022

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Acoustic rays are modified while propagating through oceanic eddies. However, due to the lack of field synchronous observation, the impact of mesoscale eddy on the acoustic propagation is less clarified. To address the issue, an eddy-acoustic synchronous observation (EASO) field experiment for a mesoscale warm eddy was carried out in the slope of the South China Sea (SCS) in October, 2021. During the field experiment, a total of 105 conductivity-temperature-depth (CTD) stations, as well as a zonal acoustic survey line through the center of the warm eddy, were obtained. The vertical structures of temperature and salinity indicate that the warm eddy is surface-intensified with temperature and salinity cores confined within depths from 70 m to 200 m and 10 m to 70 m, respectively. The acoustic observation shows two obvious convergency zones (CZs) at about 39 km and 92 km in the eastern half acoustic line, and one convergency zones (CZ) at about 25 km in the western half acoustic line. By comparing with the none eddy circumstance, the respective impacts of the topography and warm eddy are quantitatively analyzed with a ray-tracing model. The results indicate that the topography shortens the horizontal span of the CZ by 11.4 km, while the warm eddy lengthens it by 1.7 km. Additionally, the warm eddy shallows the depth and broadens the width of the CZ by 32 m and 1.4 km, respectively. The anisotropy of 3D sound fields jointly influenced by the warm eddy and the local topography show that the distance differences of the first CZs in different horizontal directions can be as long as 31 km.

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Effects of mesoscale eddies on the spatial coherence of a middle range sound field in deep water

Cited by 3 publications

References 20 publications

A FEM Flow Impact Acoustic Model Applied to Rapid Computation of Ocean-Acoustic Remote Sensing in Mesoscale Eddy Seas

A FEM Flow Impact Acoustic Model Applied to Rapid Computation of Ocean-Acoustic Remote Sensing in Mesoscale Eddy Seas

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

Observation of a mesoscale warm eddy impacts acoustic propagation in the slope of the South China Sea

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