Accession Number:

ADA636779

Title:

NPAL Data Analysis

Descriptive Note:

Corporate Author:

SCIENCE APPLICATIONS INC LA JOLLA CA

Personal Author(s):

Report Date:

1999-09-30

Pagination or Media Count:

7.0

Abstract:

ATOCNPAL Propagation Modeling. A scientific mystery has emerged from the analysis of bottom-mounted SOSUS hydrophone recordings of the broadband ATOCNPAL source located just north of Kauai. Strong, robust arrivals are observed from several hundred meters below the turning point of predicted rays. This issue has been looked at extensively by Dr. Brian Dushaw of the UW-APL and Dr. John Colosi of the Woods Hole Oceanographic Institute. To date, the observations remain unexplained. Internal wave scattering is generally the first idea broached on the subject but work by Colosi and Heaney has shown that internal waves are not responsible for significant diffraction of a wavefront caustic in the vertical, particularly for high-angle rays. Here we will present the puzzle and show our explanation of the measurements based upon broadband parabolic equation and normal mode modeling as well as ray based modeling techniques. The ATOC and NPAL programs have been pioneers in examining the feasibility of global climate monitoring using long range acoustics. One of the decisions made during the early stages of this study was to place sources near shore where the local bathymetry interacts with the sound channel. This was done to eliminate the problem of source motion of a moored source in deep water and to facilitate the delivery of power to the source via underwater cables to land. This study examines the complex interaction of the sound with the local bathymetry before entering the deep ocean. The implications to the climate-monitoring field are significant.

Subject Categories:

  • Meteorology
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE