A review of seafloor scattering measurements from silty to sandy seafloors and implications for remote seafloor characterization

The performance of active sonar systems often depends on the acoustic properties of the seafloor, which in turn depends on the bulk properties of the seafloor, the roughness of the sediment–water interface, volume inhomogeneities and the influence of discrete scatterers on and within the seafloor. Furthermore, variations in near-bottom hydrodynamics and biological activity can alter seafloor properties on various temporal and spatial scales. In this talk, we present an overview of the current state of seafloor backscattering measurements with a focus on implications for remote seafloor characterization. To this end, we have compiled a large dataset of reported seafloor scattering measurements with sediment types varying from silts to coarse sands at frequencies between 1 and 500 kHz. These results are compared to time series of seafloor scattering measurements collected in a series of experiments lasting from 2 weeks to 5 months in two shallow water locations near Portsmouth, NH. The dependence of seafloor scattering measurements on grazing angle, grain size, and frequency is presented, and comparisons are made to predictions from the small-slope approximation model. The results are discussed with a focus on providing context for sources of variability among reported measurements of seafloor scattering.