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P. Borejko:
"A coastal wedge propagation model including shear in an absorptive bottom";
Talk: The 2nd International Conference and Exhibition on Underwater Acoustics, Rhodes, Greece (invited); 2014-06-22 - 2014-06-27.

A representative model of the propagation of underwater sound on a coastal wedge is that of an acoustic wave in a wedge-shaped layer of fluid over a penetrable bottom (penetrable wedge). Acoustic propagation in penetrable wedge model has been analyzed by various methods since the early 1980s, but there have been a few observations of the predicted three dimensional (3-D) propagation effects. It was not until 2007 that the 3-D sound was quantitatively measured in a pair of acoustic transmission tests on the Florida shelf [Heaney and Murray, J. Acoust. Soc. Am. 125(3), 1394-1402, March, 2009]; and then modeled by applying highly accurate 3-D hybrid [Heaney et al., J. Acoust. Soc. Am. 131(2), 1680-1688, February, 2012] and adiabatic-mode [Ballard, J. Acoust. Soc. Am. 131(3), 1969-1977, March, 2012] based approaches.
In this paper, the method of generalized ray is applied to acoustic propagation calculations in a 3 [deg] wedge of water over an exposed low-loss limestone bottom, in which, like on the Florida shelf, the shear wave speed is slightly less than the speed of sound in the water. The predicted 3-D cross-slope propagation effect is that some acoustic signals coming in along paths of multiple bottom interactions (in-shore refracted paths, propagating up the slope and back to the receiver) may substantially be stronger than those coming in along paths of only a few bottom interactions (direct paths, traveling near the straight source-to-receiver path that is parallel to the wedge apex). This theoretical prediction is consistent with observations of two distinct signal arrivals in the above-mentioned tests: one signal coming in along a direct path; and the other, sometimes substantially stronger than the direct arrival, coming in later along an in-shore refracted path.

Acoustics, Coastal Wedge, 3-D Propagation