Accession Number : ADA258056


Title :   Examination of Three-Dimensional (3-D) Effects on Sound Propagation through Mesoscale Features Using 3-D Coupled Mode Theory


Descriptive Note : Master's thesis


Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA


Personal Author(s) : Binhlam, Jacqueline M


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a258056.pdf


Report Date : Jun 1992


Pagination or Media Count : 79


Abstract : A study of the three dimensional (3-D) effects of mesoscale variability on underwater sound propagation is conducted by interfacing the Chiu-Ehret 3-D acoustic coupled mode (CM) model with a forecasted sound speed field generated by the Harvard open ocean model (HOOM) This research concentrates on the sensitivity of the acoustic wave field to source depth and location with respect to a core ring in the Gulf Stream system for a 50 Hz sound source. The inclusion of the exact 3-D physics in acoustics modeling requires substantial computer resources. For this reason, it is very desirable to determine when the simpler adiabatic or Nx2-D approximations may be used. To achieve this goal, exact 3-D acoustic coupled mode model calculations are compared to results from the adiabatic approximation and Nx2-D approximation in terms of transmission loss and phases and amplitudes of individual mode modulation envelopes. The results show that the accuracy of the adiabatic and Nx2-D approximations depend strongly on the radial and transverse sound speed gradients along the track and the acoustic quality considered. Underwater sound propagation modeling.


Descriptors :   *SOUND TRANSMISSION , *ADIABATIC CONDITIONS , *UNDERWATER SOUND SIGNALS , SOURCES , CORES , MODELS , COMPUTERS , ACOUSTIC WAVES , OCEANS , MODULATION , OCEAN MODELS , TRANSVERSE , GRADIENTS , TRANSMISSION LOSS , UNDERWATER SOUND , GULF STREAM , AMPLITUDE , RINGS , SOUND , SENSITIVITY , DEPTH , THREE DIMENSIONAL , QUALITY


Subject Categories : Physical and Dynamic Oceanography
      Acoustic Detection and Detectors
      Acoustics


Distribution Statement : APPROVED FOR PUBLIC RELEASE