Bottom scattering measurements in shallow water
Sonar performance predictions of reverberation in shallow water rely upon good estimates of the bottom scattering strength. However, little is understood about bottom scattering in shallow water inthe frequency range 400 - 4000 Hz, particularly its dependency upon frequency and its relationship tothe physical properties of the seafloor. In order to address these issues, new measurementtechniques have been developed to probe the frequency and angular dependency of bottom scattering strength. The measurement techniques also appear to be capable of revealing the physical mechanisms that give rise to the scattering. Several experimental techniques will be described, including use of coherent and incoherent sources (lightbulbs). The general experimental approach is also described which includes auxiliary acoustic and geoacoustic measurements designed to allowexploration of the relationship between bottom scattering and the physical properties of the bottom.Measurement and modeling results for two shallow water sites are presented. At one site, the scattering appeared to arise from at or near the water-sediment interface. At the other site, scattering from a 25 m sub-bottom horizon is clearly apparent in the data at and below 1800 Hz.
Holland, Charles W.;
Hollett, Reginald D.;