PHASE FLUCTUATIONS OF THE SOUND FIELD DUE TO INTERNAL WAVES IN SHALLOW WATER

Distortion of the phase front of the sound field from the point source in shallow water in presence of intense internal waves (IW) is considered. In absence of IW phase front has cylindrical shape with axis passing through the source perpendicular to the horizontal plane. One of the main peculiariti...

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Bibliographic Details
Main Authors: B. G. Katsnelson, A. V. Tshoidze
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Published: 2007
Subjects:
Barents Sea
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.492.8704
http://www.sea-acustica.es/WEB_ICA_07/fchrs/papers/unw-04-010.pdf
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Summary:Distortion of the phase front of the sound field from the point source in shallow water in presence of intense internal waves (IW) is considered. In absence of IW phase front has cylindrical shape with axis passing through the source perpendicular to the horizontal plane. One of the main peculiarities of distortion in presence of IW is frequency and modal dependencies of characteristics of this distortion. Fluctuations of the phase front is considered within the framework of theory “vertical modes and horizontal rays ” or PE in horizontal plane. It is shown that mentioned fluctuations can be measured using horizontal line array together with modes filtering. Theoretical estimations and numerical modeling is carried out for conditions of Mid Atlantic bight and Barents sea. It is known that intense IW cause significant fluctuations of the sound field in shelf zone of the Ocean. It is shown in [1,2] that significant fluctuations of the sound intensity take place if acoustic track is approximately parallel to wave front of IW due to horizontal refraction. Remark that fluctuations of sound phase (or in ray language fluctuations of direction of propagation in horizontal place) also are of great interest. Practically they can be measured using horizontal line array (HLA) simultaneously with modes filtering. Let’s consider sound propagation in 3D shallow water waveguide in presence IW (Fig.1). Water layer is restricted by the surface (X,Y), and plane Hz = , where Z-axis is directed downward. In water layer we have density distribution)(zρ and sound speed profile),,()(),, ( 0 zyxczczyxc δ+ = where some unperturbed sound speed profile and)(0 zc),, ( zyxcδ perturbation due to IW.

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