Statistical Properties of the Sea Surface Sound Dipole Source
Abstract
A broadband measurement (40 to 4000 Hz) of the vertical directional spectrum of the underwater ambient acoustic filed was made in an acoustically isolated area where the ambient is dominated by well documented local sea conditions. Measurements, made over a one-year period, sampled a wide range of sea conditions and made possible a statistical analysis of the effects of the sea surface condition on the acoustic field. Having the total directional spectrum, unperturbed by long-distance sources, allowed the partitioning of the measurement into multiple source types; each type distinguished by its unique vertical directional pattern. An important component of the sea surface- generated radiation is a diffuse distribution of vertical dipole sources. A unique property of this data analysis is that the dipole source strength 'area density' is found by matching only that part of the total measured pressure field exhibiting a dipole pattern. This is accomplished by parametric spectral estimation procedures. The frequency spectrum of the dipole source strength is found to be a bandpass function whose parameters are statistically related to the wind-generated surface friction velocity. Results of the analysis contribute an important element to an accurate modeling of the space-time statistics of sea surface sound.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1990
- Accession Number
- ADA230811
Entities
People
- R. M. Kennedy
Organizations
- Naval Underwater Systems Center