Surface Backscattering Strengths Measured with Explosive Sound Sources

Abstract

The scattering strength of the sea surface was measured for a range of wind velocities, grazing angles, and frequencies, in octave bands in the frequency range from 400 to 6400 cps. An empirical equation was obtained relating the scattering strength of the sea surface to the above variables, for grazing angles below 40°. At low grazing angles, scattering of sound from a subsurface layer of isotropic scatterers, probably of biological origin, frequently masked the reverberation due to scattering from surface roughness. For a given wind speed, the scattering strengths measured in this study at grazing angles below 20° were appreciably less than those obtained by other observers at higher frequencies. At higher grazing angles, of the order of 40°, there was little systematic difference between the measurements made at high and low frequencies.

Broadband Models for Predicting Bistatic Bottom, Surface, and Volume Scattering Strengths

“…The residual standard error r se for fitting the resultant new SSS model to the full deep-water data set was 2.4 dB, compared to 4.1 dB when applying the Chapman-Harris [64] empirical formula. (When restricted to data corresponding to frequencies below 1000 Hz, the new model had an r se of 2.2 dB, compared to 4.1 and 3.1 dB when applying the Chapman-Harris and Ogden-Nicholas-Erskine [65] empirical formulas, respectively.…”

“…This model offers significant advances over previous (purely empirical, monostatic) algorithms [64][65], namely physics-based descriptions of scattering from both the rough air-sea interface and subsurface bubbles; fully bistatic calculations; and applicability to a broader range of frequencies.…”

Modeling the power delay profile of underwater acoustic channels — The effects of out-of-plane scattering and reverberation

“…3 shows Rev3D results for location A, to be compared to the upper panel of Fig. 1 [17] together with Ogden-Erskine [18] (for the pertinent wind speed 10 m/s) scattering-strength functions for bottom and surface, respectively. These functions are applied although they primarily concern backscattering, and the patch contributions are here considered to be independent of the bistatic angle β between the azimuths of the patch-tosource and patch-to-receiver directions.…”

Dynamics of Langmuir circulation in oceanic surface layers

“…This difference in the light seen been the cells will be reflected in differences in the productivity of the cells. oAcoustic Backscatter and Ambient Noise: The organized motions associated with the cells create curtains of bubbles The scattering from these bubble plumes has been invoked as an explanation for the degradation of active sonars in high sea states (Chapman and Harris, 1962). The oscillation of bubble plumes has been suggested as an explanation for increase in ambient noise in the 500-800 Hz band.…”