title: Head wave correlations in ambient noise.
abstract: Ambient ocean noise is processed with a vertical line array to reveal coherent time-separated arrivals suggesting the presence of head wave multipath propagation. Head waves, which are critically propagating water waves created by seabed waves traveling parallel to the water-sediment interface, can propagate faster than water-only waves. Such eigenrays are much weaker than water-only eigenrays, and are often completely overshadowed by them. Surface-generated noise is different whereby it amplifies the coherence between head waves and critically propagating water-only waves, which is measured by cross-correlating critically steered beams. This phenomenon is demonstrated both experimentally and with a full wave simulation.
authors.affiliation: Metron Scientific Solutions, 1900 Southwest 4th Avenue, Suite 89-01, Portland, Oregon, 97201, USA gebbie@metsci.com.
authors.forename: John
authors.initials: J
authors.lastname: Gebbie
authors.affiliation: Northwest Electromagnetics and Acoustics Research Laboratory, Department of Electrical and Computer Engineering, Portland State University, 1900 Southwest 4th Avenue, Suite 160, Portland, Oregon 97201, USA siderius@pdx.edu.
authors.forename: Martin
authors.initials: M
authors.lastname: Siderius