Correlation of Ambient Sea Noise

Abstract

Space-time correlations of ambient sea noise were measured with vertical pairs of hydrophones in the frequency range of 125–1131 cps and with horizontal pairs in the range of 22–63 cps at various sea states (SS) in the deep ocean. The experimental results are compared with those obtained from theoretical models of a uniform distribution of surface-noise sources, radiating with an intensity pattern of cos2nα, where α is the angle from the vertical. At SS5 and frequencies above 400 cps, a good fit to the experimental spatial correlations as well as to the principal peak of the space-time correlation is obtained for n = 1. At the same sea state, the 250-cps data correspond to n = 12. In the low-frequency range, omnidirectional noise sources explain the experimental data up to and including SS5. The model does not give a sufficient explanation for the space-time correlations at SS3 in the range 400–1131 cps.