Accession Number : ADA293294

Title :   A Review of the Acoustic Propagation Characteristics Near the SAS Site Using Archival CTD Profiles.

Descriptive Note : Technical rept.,

Corporate Author : WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB

Personal Author(s) : Reynolds, Steve ; Henyey, Frank ; Williams, Kevin ; Ewart, Terry

PDF Url : ADA293294

Report Date : MAR 1995

Pagination or Media Count : 25

Abstract : The Synthetic Aperture Sonar component of the Coastal Mixing and Optics Experiment is planned for August of 1996, south of Woods Hole at 40.5 deg N, 70.5 deg W. Water depth is about 70 m. Thirty archival CTD casts from the months of July and August have been used to study the likely acoustic propagation conditions near the site. The archival casts show two-layer stratification with high speed surface water and deeper slower water separated by a high-gradient region. For a transmitter 10 m above the bottom, nearly horizontal rays occur at ranges near the transmitter. As range increases, at least two caustics are passed. Between the caustics, two ray paths that traverse the high-gradient depth region are present along with the near-horizontal path. Both the near-horizontal and the paths that sample the high-gradient region are of interest. Casts near the proposed site from depths of 60-80 m, indicate conditions favorable for measuring both types of paths. At deeper sites, the propagation region between the caustics moves beyond our maximum range of 1000 m. At shallower sites, separating arrivals will be difficult because the ray pattern is shortened in range.

Descriptors :   *SONAR SOUND ANALYZERS, *SYNTHETIC APERTURE SONAR, COASTAL REGIONS, PATHS, DEPTH, SURFACE WATERS, SOUND TRANSMISSION, HORIZONTAL ORIENTATION, MIXED LAYER(MARINE), GRADIENTS, ACOUSTIC PROPERTIES, CAUSTICS.

Subject Categories : Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE