Influence of Surface Roughness and Bubbles on Sea Surface Acoustic Backscattering (Der Einfluss von Seegangsrauhigkeit und Blasen auf die Akustischen Rueckstreueigen-Schaften der Meeresoberflaeche)

摘要

The results from a recent sea surface acoustic scattering experiment, which was conducted in the North Sea, are presented with accompanying sea surface roughness parameters and subsurface bubble information. The acoustic data were obtained utilizing a high-resolution (narrow beamwidth) pulsed parametric sonar transmitter and conventional receiver. Scattering strength values were obtained as a function of frequency (3-18 kHz) and grazing angle (15 to 90) for differing sea surface roughness and wind speed conditions. The dominant backscattering mechanisms are bubbles at high wind speeds and low grazing angles and the high frequency ocean wavenumber spectrum at low wind speeds and all grazing angles. In an intermediate wind speed regime, the time history of backscattering shows strong fluctuations, which are caused by both scattering mechanisms.