Bottom Interaction in Ocean Acoustic Propagation
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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This project addresses the effects of environmental variability induced by ocean internal waves, internal tides and mesoscale processes, and by bathymetric features including seamounts and ridges, on the stability, statistics, spatial distribution and predictability of broadband acoustic signals... quote from the Ocean Acoustics web page. The long-term objective here is to understand the dominant physical mechanisms responsible for propagation and scattering in the deep ocean where the sound channel is not bottom limited. Understanding long range acoustic propagation in the ocean is essential for a broad range of Navy applications such as i the acoustic detection of ships and submarines at long ranges, ii avoiding detection of ships and submarines, iii long range command and communications to submerged assets, and iv improved understanding of the environment through which the Navy operates. Bottom interaction plays a significant role in the physics of both short and long-range ocean acoustic propagation and impacts physical models of both signals and ambient noise. As discovered on NPAL04 for controlled sources at long range 500-3200km in deep water and frequencies around 75Hz, the sound field at the bottom is much more complex than the sound field in the ocean. The deep seafloor arrival pattern is not entirely random, but has some components that are regular, coherent and repeatable.