Emergence of striation patterns in acoustic signals reflected from dynamic surface waves

TitleEmergence of striation patterns in acoustic signals reflected from dynamic surface waves
Publication TypeJournal Article
Year of Publication2014
AuthorsChoo Y., Seong W., Song H.
JournalJournal of the Acoustical Society of America
Date Published2014/09
Type of ArticleArticle
ISBN Number0001-4966
Accession NumberWOS:000342205700018
Keywordschannels; gravity water-waves; high-frequency; propagation; scattering; sea-surface; shallow-water; sound; transmissions

A striation pattern can emerge in high-frequency acoustic signals interacting with dynamic surface waves. The striation pattern is analyzed using a ray tracing algorithm for both a sinusoidal and a rough surface. With a source or receiver close to the surface, it is found that part of the surface on either side of the specular reflection point can be illuminated by rays, resulting in time-varying later arrivals in channel impulse response that form the striation pattern. In contrast to wave focusing associated with surface wave crests, the striation occurs due to reflection off convex sections around troughs. Simulations with a sinusoidal surface show both an upward (advancing) and downward (retreating) striation patterns that depend on the surface-wave traveling direction and the location of the illuminated area. In addition, the striation length is determined mainly by the depth of the source or receiver, whichever is closer in range to the illuminated region. Even with a rough surface, the striation emerges in both directions. However, broadband (7-13 kHz) simulations in shallow water indicate that the longer striation in one direction is likely pronounced against a quiet noise background, as observed from at-sea experimental data. (C) 2014 Acoustical Society of America.

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