Research on the influence of internal waves on sound propagation in shallow sea negative gradient environment
As a kind of fluctuation in the density stable stratified seawater,the internal wave of the ocean causes drastic changes in the internal structure of seawater such as temperature and salt during the horizontal and vertical exchange of sea-water,and has a great impact on the underwater sound velocity gradient structure.Based on the internal wave phenomenon captured in a certain sea area,the acoustic propagation characteristics of different sound sources in a negative gradient envir-onment are studied from the aspects of detection depth,reception depth,frequency,and phase variation.The results show that the existence of internal waves can increase the propagation loss and reduce the detection distance of sonar,and with the increase of the depth of the sound source,the propagation loss decreases first and then increases,and the sound propagation loss is the smallest when the sound source is at half of the maximum amplitude of the internal wave.A similar conclusion is reached for the propagation loss at different reception depths,and the corresponding phase change is the smallest when the propagation loss is large,and vice versa.
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