EFFECTS OF PROPAGATING INTERNAL WAVES ON SHALLOW-WATER ACOUSTIC PROPAGATION DURING THE TRANSVERSE ACOUSTIC VARIABILITY EXPERIMENT OF 2008

Open Access
Author:
Smith, Chad M
Graduate Program:
Acoustics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • David Bradley, Thesis Advisor
  • Thomas B Gabrielson, Thesis Advisor
  • Richard Lee Culver, Thesis Advisor
Keywords:
  • shallow-water
  • internal wave
  • acoustic
Abstract:
During August of 2008, the Transverse Acoustic Variability EXperiment (TAVEX) was carried out within the northern East China Sea southwest of Jeju Island, South Korea. Water depth of the experimental area varied around 70 to 85 m and the site was located approximately 100 km southwest of Jeju and 300 km northwest of a continental shelf break. Data collected includes towed conductivity, temperature, and depth (CTD) measurements of the water column, moored temperature recordings, bathymetry and acoustical sediment properties, as well as horizontal line array (HLA) recordings of CW and LFM pulsed sources. The focus of this measurement experiment is to understand and model the effects of internal waves on the acoustic signals received by a bottom-mounted HLA in the shallow-water environment within this region. Specifically, to evaluate the effects of the internal wave field on coherence of the HLA. The research presented in this thesis is a portion of this work. An overview of the TAVEX 2008 experiment is given, and the effects of internal waves on acoustic variation across the HLA are considered using a spectral approach. This analysis includes examination of harmonic variations in received acoustic pressure. Internal wave characteristics measured during the CTD tow, modeling of internal wave and acoustic fields, and the comparison of computational models with experimental acoustic data are presented. Techniques used for modeling of the acoustic field include both analytical ray and computational parabolic equation (PE) methods.