Modeling of Ocean Surface Spectrum and Surface Scattering - Applications to Reverberation Prediction in the AAUS Program

Abstract

Current scattering theories for sound interaction with the ocean surface and empirical descriptions of the ocean surface wave spectrum are examined for incorporation into the NRL Reverberation Model (RASP). The intent is to provide surface scattering strength estimates using such theories to augment the empirical data bases in surface scattering strength already included in RASP. Since the input surface wave spectrum plays a critical role in determining the scattering strength, a comprehensive assessment of available empirical models of surface wave spectra was performed and the most updated version of the Pierson model was selected for use in combination with the azimuthal distribution model proposed by Mitsuyasu et al. This study focussed on those scattering theories that perform best in the low frequency (< 500 Hz), low-grazing angle (<20 deg) regime. As a result, scattering models such as the small perturbation method and the composite roughness approach were selected for incorporation into RASP in addition to two empirical models, Martin and Chapman- Harris. Illustrations of the surface wave two-dimensional spectrum are presented, and sample computations of the scattering strength using the selected models are given for different combinations of the principal parameters, which include frequency, wind speed, wind direction, and scattering geometry. These newly-developed capabilities satisfy quite adequately immediate computational requirements, and will be incorporated into RASP. Future research needs are identified which will enable better understanding and prediction of the spectral content and stochastic fluctuations of ocean surface-scattered acoustic fields.

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Document Details

Document Type
Technical Report
Publication Date
Jun 23, 1989
Accession Number
ADA210127

Entities

People

  • B. B. Adams
  • E. R. Franchi
  • T. D. Ngoc

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Acoustic Frequencies
  • Acoustic Scattering
  • Acoustic Waves
  • Acoustics
  • Computer Programs
  • Databases
  • Diffraction
  • Frequency
  • Frequency Bands
  • Geometry
  • Grazing Angles
  • Integral Equations
  • Reverberation
  • Scattering
  • Spectra
  • Surface Waves
  • Waves

Readers

  • Acoustical Oceanography.
  • Atmospheric Science / Meteorology, specifically Wind Wave Turbulence.
  • Computational Modeling and Simulation