Mode and PE predictions of propagation in range-dependent environments: SWAM'99 workshop results

Abstract

Three numerical acoustic models, a coupled normal-mode model (C-SNAP),

an adiabatic normal-mode model (PROSIM) and a parabolic equation model (RAM), are applied to test cases defined for the SWAM'99 (Shallow-Water Acoustic Modeling) workshop, Naval Postgraduate School, Monterey (CA), 1999. The test cases consist of three shallow-water (flat bottom) scenarios with range-dependent sound-speed profiles imitating internal wave fields and a

shelf-break case, with range-dependent sound-speed profiles and bathymetry. The bottom properties in all cases are range independent and modelled as a homogeneous fluid halfspace. The results from the modelling are presented as

transmission loss for selected acoustic frequencies and source-receiver geometries and as received time series. The results are compared in order to evaluate

the effect of applying different propagation models to the same range-dependent underwater environment. It should be emphasized that the propagation analysis is not an attempt to benchmark the selected propagation models, but to

demonstrate the performance of practical, range-dependent models based on different approximations, in particular underwater scenarios.