Measurements of Volume Scattering from a Deep Scattering Layer

Abstract

Volume-reverberation measurements were made to determine scattering strengths of a deep scattering layer located approximately 250 miles east of Nassau during 18 July 1965. Explosive charges of 2 lb of TNT, used as sound sources, were detonated throughout an 18-h period. Both 13- and 1-oct-band analyses were performed on the data. Scattering strengths, presented in the frequency region from 1.6 to 25.6 kcps, show an increase in amplitude with an increase in frequency. The diurnal change in scattering strengths caused by the deep-scattering-layer migration generally diminishes as frequency is increased. The 13-oct levels range from −82 to −53 dB with the highest levels occurring in the 16.0- and 20.0-kcps bands. The diurnal change in the level of the scattering strength is most pronounced in the 13-oct band centered at 3.2 kcps. Comparisons of scattering-strength characteristics with other published data show agreement in the amount of diurnal variation for a given octave band, diminution of diurnal variation with increased frequency, and an amplitude increase of scattering strengths with increased frequency.