Measurements of Backscattering from the Sea Surface

Measurements of ocean‐surface backscattering were made off Nassau in 2500‐f water using 2‐lb TNT charges as acoustic sources. Analysis in octave frequency bands between 0.8 and 12.8 kc/sec shows surface backscattering decreasing down to grazing angles of 2° and confirms that scattering strength is proportional to frequency and wind velocity, with wind velocity becoming increasingly significant as grazing angle is decreased. Volume backscattering predominates over surface backscattering at low wind velocities and small grazing angles; the volume backscattering is presumed to be due to the presence of a layer of large numbers of microscopic marine life. General agreement was obtained on backscattering coefficients at grazing angles where previously published data are available for comparison.