Measurements of the Backscattering of Underwater Sound from the Sea Surface

Abstract

Measurements of the backscattering of 60-kc sound from the surface of the sea have been made in Puget Sound in an effort to relate the strength of the scattered sound to the character of the surface. In addition to providing a means of predicting reverberation levels, an attempt has been made to obtain a better understanding of the fundamental mechanism of scattering at the air-water boundary. The reverberation measurements are presented, along with observations of several oceanographic and meteorological parameters. An examination of the data allows the following conclusions: (1) reverberation pulses from an area of several square yards follow a Rayleigh distribution; (2) reverberation cannot be directly related to the wave height, but is closely correlated with wind speed; (3) reverberation increases with wind speed to a speed of 14 knots, and remains constant for higher wind speeds; and (4) reverberation is independent of the angle with the surface for angles from 20 to 60 degrees, but drops off rapidly as the angle is decreased below 20 degrees.