Accession Number:

ADA508157

Title:

Forward Sound Propagation Around Seamounts: Application of Acoustic Models to the Kermit-Roosevelt and Elvis Seamounts

Descriptive Note:

Doctoral thesis

Corporate Author:

MASSACHUSETTS INST OF TECH CAMBRIDGE JOINT PROGRAM IN APPLIED OCEAN SCIENCE AND ENGINEERING

Personal Author(s):

Report Date:

2009-06-01

Pagination or Media Count:

279.0

Abstract:

The Basin Acoustic Seamount Scattering Experiment BASSEX of 2004 was conducted to measure forward-scattering around the Kermit-Roosevelt Seamount Complex in the Northeast Pacific. The BASSEX experiment was focused on the bathymetric effects on acoustic propagation, in particular, on direct blockage, horizontal refraction, diffraction, and scattering by the seamounts. A towed hydrophone array, with 64 sensors cut for 250Hz 3m spacing, was used to measure the signals transmitted from the aforementioned broadband sources at many locations around the Kermit-Roosevelt and Elvis seamounts. Utilizing the measured broadband signals from the towed array, the size of the shadow zone was obtained. The measured data in the BASSEX experiment strongly support the understanding of the complicated phenomena of sound propagation around the seamounts. In addition, the experimental data could be used to validate current 2D and 3D theoretical models and develop new models to properly realize the sound propagation with such complicated phenomena. In this thesis, the reconciliation between the measured pulse arrivals from the BASSEX experiment and various two-dimensional 2D and three-dimensional 3D theoretical models is carried out to investigate the physical characteristics of the sound propagation around seamounts First, the 2D Parabolic Equation PE model and the 2D ray tracing model are used to reconcile each ray arrival with the BASSEX experiment in terms of arrival time and grazing angle. We construct a sound speed field database based on the sound speed profiles from the BASSEX experiment, World Ocean Atlas WOA 2005, and CTD casts using the objective analysis. Second, 3D broadband sound propagation around a conical seamount is investigated numerically using the 3D spectral coupled-mode model W. Luo, PhD Thesis, MIT, 2007.

Subject Categories:

  • Physical and Dynamic Oceanography
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE