PE modeling of upslope propagation data.

Abstract

The analysis and interpretation of underwater acoustic propagation data measured in regions of complex bathymetry (e.g., near continental slopes) can be enhanced by using a full-wave, range-dependent propagation model. Such models are particularly important at low frequencies, where sub-bottom penetration of sound can be significant. With the recent development of a two-way parabolic equation (PE) formalism [e.g., M. D. Collins etal., J. Acoust. Soc. Am. 90, 2277 (1991)], fast and accurate modeling of forward- and backscattered waves in range-dependent media can be realized. For propagation in an idealized wedge-shaped waveguide, the outgoing field computed with this two-way PE model compares well with the total field given by a more computationally intensive, coupled-mode model. In this paper, the formulation of a two-way PE model is used to interpret shot data recorded during an upslope experiment off the west coast of Canada. The shot waveforms were received on a 1200-m towed line array that opened range along a 15-km track. Over this endfire propagation run, the water depth decreased from 1500 to 500 m. The measured data were processed as a function of frequency, range, and vertical angle and compared to the forward-scattered component of the two-way PE field.