CORRELATION OF DEEP OCEAN NOISE (0.4-30 HZ) WITH WIND, AND THE HOLU SPECTRUM - A WORLDWIDE CONSTANT

One year of ambient ocean noise data, 0.4 to 30 Hz, from the Wake Island hydrophone array in the northwestern Pacific are compared to surface wind speeds, 0-14 m/s (0-28 kn). Between 0.4 and 6 Hz, noise levels increase with wind speed at rates of up to 2 dB per m/s until a saturation is reached having a slope of about -23 dB/octave and a level of 75 dB relative to 1 muPa/ square-root Hz at 4 Hz. This noise saturation, called the ''Holu Spectrum,'' likely corresponds to saturation of short-wavelength ocean wind waves. It is probably a worldwide constant. Between 4 and 30 Hz, noise also increases with wind speed at rates of up to 2 dB per m/s, but no saturation level is observed and the slope increases to about 4 dB/octave. This may be acoustic noise from whitecaps. On a hydrophone less than 3 km from Wake, noise between 0.5 and 10 Hz increases with wind speed at a rate up to 2 dB per m/s, but absolute noise levels are significantly higher than levels on the other hydrophones more distant from Wake, and no saturation is apparent. Surf breaking a inst the shore of the island is the probable source of this noise.