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3D sound intensity variability in shallow water in presence of internal waves in SWARM'95 experiments

Badiey M., Katsnelson B., Lynch J., Pereselkov S., Siegmann W.

Hydroacoustics

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2003

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Vol. 6

101--112

EN

Broadband shot signal data are analyzed from the SWARM'95 experiment to investigate acoustic variability in presence of internal solitons. A 10 to 15 minute temporal variations in the intensity of the received signals were observed. These temporal variations are azimuthally dependent on variability of water column in the presence of internal solitary waves. These fluctuations should be explained by significant horizontal refraction (3D-effects) taking place when orientation of acoustic track is close to direction of the wave front of internal solitons. Analysis on the base of both equation of vertical modes/horizontal rays and PE in horizontal plane is carried out, good agreement between theoretical calculations and experimental data is obtained.

2

Acoustic field in shallow water at presence of internal solitons

Katsnelson B., Pereselkov S.

Hydroacoustics

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2000

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Vol. 3

115--120

EN

In the paper the transformations of sound field structure conditioned by packets of internal solitons (IS) are considered within the framework of the theory "horizontal rays and vertical modes". We analyze a two cases of the acoustic trace orientation in relation to front of IS. It is shown that acoustic effects have resonant frequency dependence when internal solitons propagate along trace. It is ascertained as well, that the IS can lead to formation of "dynamic" horizontal sound channels and as result the significant temporary fluctuations of acoustic signals will be on an acoustic trace oriented along front of internal waves. The results presented in the paper can be used as basis for the remote monitoring of the characteristics of internal solitons in ocean shelf.

3

Horizontal refraction and acoustic signals fluctuations caused by internal waves packets in shallow water

Katsnelson B., Pereselkov S.

Hydroacoustics

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1999

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Vol. 2

307--312

EN

The subject of the paper is to consider the propagation of low frequency sound field in shallow water in presence of soliton-like internal waves (SLLW). It is supposed that shallow water parameters are closed lo ones of acoustic trace in Yellow Sea. We assume as well that SLIW spread across stationary acoustic trace. The problem of sound propagation is considered within the framework of 3-D model of the shallow water. The theory of "horizontal rays and vertical modes" is applied to take into account influence of horizontal refraction due to SLIW. As shown in the paper SLIW lead periodically to "focusing" and "defocusing" of the horizontal rays. The estimations of the sound fluctuations due to SLIW demonstrates that value of fluctuations can reach up to 10-20 dB (between moments of the "focusing" and "defocusing"). The results presented in the paper can be used as basis of remote sensing of the internal waves packets in shallow water.

4

Estimation of hydroacoustic parameters of boftom in shallow water using low-frequency FM signals

Grigoryev V., Katsnelson B., Petnikov V.

Hydroacoustics

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1999

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Vol. 2

91--94

EN

Method of data inversion for geoacoustic parameters of boftom using FM acoustic signals is presented Frequency spectra of received signals are taken as input data for application of Matched Field Processing (MFP) method. For estimation of boftom parameters we use the two-components model of sediment. As a result of matching we obtain relationship between two mechanisms of loss: energy absorption and volume scattering within boftom sediment.