Numerical investigation of rough surface scattering in a fetch-limited environment using a parabolic equation model

Abstract

When compared to the open ocean, the littoral environment is responsible for a greater dispersion of acoustic energy per volume due to scattering from the sea surface, sea floor, topographic features, and disharmonious regions within the volume. Of particular interest is the modeling of acoustic energy as it is reflected and dispersed by a rough sea surface based on an empirical fetch-limited ocean wave spectrum, and how such modeling compares with measured data. Following the method of Tappert and Nghiem-Phu [J. Acoust. Soc. Am. Suppl. 1 77(2), S101 (1985)], a formulation for scattering from a rough surface has been developed that includes results from analysis of data [Hasselmann et al., JPO 10, 1264–1280 (1980)] collected during the Joint North Sea Wave Observation Project. The formulation is integrated into the Monterey–Miami Parabolic Equation Model [Smith, J. Comput. Acoust. 9, 243–285 (2001)]. The model is validated by comparing to a unique set of experimental data collected in a fetch-limited region. Arrival time and arrival-angle fluctuations are examined and compared with field data.