Distant bottom reverberation in shallow water

The effects of rough sea surface on the long-range bottom reverberation in shallow seas are studied by the coupled mode reverberation theory. The scattering effect caused by irregular rough sea surface is described by couple coefficients. The decaying rules of long-range bottom reverberation level are simulated at different sea states, and the rough sea surface effect on the coherence of distant bottom reverberation is also discussed. It is indicated that irregular upper boundary has changed the propagation effect of the shallow water waveguide, and bottom reverberation, which is dominated among other kinds of reverberation in shallow water, is affected by the sea surface scattering as the increasing sea state. Compared with other literatures, the emphasis of this paper is to present the mechanism of rough sea surface scattering by describing the transfer of energy between different modes, and the details of energy transitions between different modes which are caused by sea surface scattering are presented for different sea states. With the increasing sea state, stronger mode coupling caused by surface scattering would affect the intensity and its space coherence of bottom reverberation obviously.

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Velocity extraction of nonlinear internal waves by reverberation detecting in shallow water waveguide

Gao,

Li,

Pang

2024

Front. Mar. Sci.

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In the realm of shallow water acoustics, reverberation poses a critical challenge to active sonar systems, yet it also serves as a valuable conduit for environmental information. This study presents the findings from a 48-hour experimental investigation of reverberation and clutter in the northern Yellow China Sea, conducted in July 2014. Utilizing temperature and depth sensor arrays, we captured multiple instances of nonlinear internal waves (NIWs). Notably, the reverberation data collected by a vertical array of hydrophones revealed peculiar intensity fluctuations, which were exclusively detected by hydrophones located below the thermocline as NIWs traversed the measurement vessel. To elucidate this phenomenon, we introduce a novel coupled-mode reverberation–clutter theory. Through numerical computations, we determined both the coherent and incoherent components of the reverberation intensities, effectively accounting for the observed target-like intensity variations. The model developed herein was further employed to successfully estimate the velocity of NIWs. These anomalous reverberation characteristics could potentially pave the way for innovative methods of NIW parameter detection in shallow water environments.

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Distant bottom reverberation in shallow water

Cited by 5 publications

References 3 publications

A Coupled Mode Reverberation Theory for Clutter Induced by Inhomogeneous Water Columns in Shallow Sea

A Coupled Mode Reverberation Theory for Clutter Induced by Inhomogeneous Water Columns in Shallow Sea

Investigation of Sea Surface Effect on Shallow Water Reverberation by Coupled Mode Method

Velocity extraction of nonlinear internal waves by reverberation detecting in shallow water waveguide

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