Accession Number:

ADA191298

Title:

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

Descriptive Note:

Final rept. Oct 85-Sep 86

Corporate Author:

FORSCHUNGSANSTALT DER BUNDESWEHR FUER WASSERSHALL- UND GEOPHYSIK KIEL (GERMANY F R)

Report Date:

1987-11-12

Pagination or Media Count:

61.0

Abstract:

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. Keywords North Sea Parametric sonar Radar backscatter Roughness dependence Shallow water Waveheight dependence Wind dependence Acoustic scattering strength Backward surface scatter Bubbles Frequency dependence Grazing angle dependence High resolution.

Subject Categories:

  • Acoustic Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE