Depth dependence of noise resulting from ship traffic and wind

Under conditions of distantly generated noise, the noise level is found to decrease with depth in the mid-northeastern Pacific. These data show a decrease in noise level greater than 25 dB between critical depth and the ocean bottom. A result of this decrease is that locally wind-generated noise can be detected on near-bottom receivers for wind speeds less than 10 kn. It is shown that the noise level generated form local sources such as wind and nearby shipping is almost independent of receiver depth. The differences in spectra shape between the distant shipping noise and wind-generated noise and the low noise levels detected near the ocean bottom allow the measurement in the frequency band at 200-500 Hz of local wind noise level for wind speeds less than 10 kn