Small scale inhomogeneity and intermittency of surface scattering during the 1992 Gulf of Alaska surface scatter and air–sea interaction experiment

Abstract

An experimental and processing technique is described that provides high resolution, broadband estimates of near-surface acoustic scattering variation in time and space. Application of the technique in the 1992 Gulf of Alaska surface scatter and air–sea interaction experiment achieved approximately 1-m×5-m range and cross-range scattering resolution over the frequency range of 100–1400 Hz, with temporal changes measured over intervals of 7 s to 30 min. Results from this experiment clearly show that during high wind, high sea state conditions, the surface scattering was dominated by intense, highly localized events with spatial densities on the order of 10–100 per sq km. A significant fraction of these events endured for time scales of a few minutes only. Some of these discrete scatterers were sufficiently removed from the surface (20–30 m) to generate resolvable multipaths. Also described is the intensity and spatial density of scatterers as a function of the environmental conditions over the several day period of the experiment.