Statistical properties of the sea surface sound dipole source

A broadband measurement (40–4000 Hz) of the vertical directional spectrum of the underwater ambient acoustic field was made in an acoustically isolated area where the ambient is dominated by well‐documented local sea conditions. Measurements, made over a 1‐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 the present 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 estmation procedures. The f...