Correlation estimates of high-frequency ocean bottom backscatter

Two environmental acoustic scattering experiments have been conducted in shallow water off the coast of Florida. The ocean bottom ranged from a smooth homogeneous medium sand to one where the surface roughness was entirely due to a coarse surficial shell layer. The acoustic transmitting system used a pair of narrow-beam parametric sources operating at secondary frequencies from 20–180 kHz. The receiving system consisted of a 16-hydrophone two-dimensional spatial array with broadband capabilities to 250 kHz. Ping-to-ping correlation estimates are presented as a function of frequency, grazing angle, azimuthal angle, and environmental conditions. Cross-correlation estimates as a function of hydrophone separation, frequency, and environmental conditions are also presented.