LAUSR

Sea surface forward scattering has important effects on shallow water propagation and reverberation at mid frequencies (i.e., 1–3 kHz) under typical sea surface roughness conditions. Coupled-mode or rough surface PE modeling of these effects require averaging results over many rough surface realizations, increasing the computational effort. An alternative method is based on transport theory, where equations are developed for propagating the moments of the field, avoiding the need for utilizing rough surface realizations. Our transport theory method is based on expanding the field in unperturbed modes, and the equations of motion are for moments of the mode amplitudes. The approach has been based on keeping terms to only first-order in the surface height h(x), making the method linear in surface height. Methods for extending the approach beyond the linear model will be described, both with using realizations with coupled modes and with attempts to extend these approaches to obtain a transport theory. A key part of the approach is the use of the Differential Algebraic Equation (DAE) method in which the range-derivative of the effective boundary condition on the mean plane of the rough surface is used instead of the effective boundary condition itself. [Work supported by ONR Ocean Acoustics.]Sea surface forward scattering has important effects on shallow water propagation and reverberation at mid frequencies (i.e., 1–3 kHz) under typical sea surface roughness conditions. Coupled-mode or rough surface PE modeling of these effects require averaging results over many rough surface realizations, increasing the computational effort. An alternative method is based on transport theory, where equations are developed for propagating the moments of the field, avoiding the need for utilizing rough surface realizations. Our transport theory method is based on expanding the field in unperturbed modes, and the equations of motion are for moments of the mode amplitudes. The approach has been based on keeping terms to only first-order in the surface height h(x), making the method linear in surface height. Methods for extending the approach beyond the linear model will be described, both with using realizations with coupled modes and with attempts to extend these approaches to obtain a transport theory. A key...