Experimental Bearing Shifts As Evidence of Horizontal Refraction in a Wedge-Like Ocean
Analysis of experimental data obtained in the region of the East Australian Continental Slope has been found to be consistent with theoretical predictions of energetic horizontal refraction due to sound-slope interaction where the observed azimuthal characteristics are in accordance with both normal mode and ray theoretical solutions. The experiment, conducted with two ships (one towing a source and the other an array), started at a 400 m depth contour with an initial separation of 33 km and proceeded to deep water on a diverging but constant line of bearing course. Beamformed data bearing shifts showing changes of tens of degrees over a few hours demonstrated the dominance of horizontally refracted arrivals for this geometry. A combination of source-array positions and critical angle effects served to limit both the azimuthal extent of energy received and the total number of modes arriving at any one position.
KeywordsContinental Slope Acoustic Field Bottom Slope Depth Contour Receiver Array
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