Accession Number : ADA207664

Title :   Improvement of Three Dimensional Acoustic Field Estimation Using Tomographic Reconstructions of the Ocean.

Descriptive Note : Master's thesis,

Corporate Author : WOODS HOLE OCEANOGRAPHIC INSTITUTION MA

Personal Author(s) : Rowe, Elizabeth A

PDF Url : ADA207664

Report Date : Aug 1988

Pagination or Media Count : 57

Abstract : To determine the efficacy of tomographic reconstructions of the ocean sound speed structure in improving acoustic field predictions for source localization, a 150 km by 350 km volume of ocean 3000 meters deep was synthetically modeled to be similar to the Gulf Stream system, including an eddy and a front. The features were Gaussian, with the eddy's maximum sound speed perturbation being 10m/s and the front's maximum perturbation 15m/s. Two vertical slices through this system were inverted in a synthetic tomography experiment using linear optimal estimation theory. Inversions were also performed using XSV and satellite sea surface temperature data. Gaussian fits to the reconstructed features were constructed for use with a three dimensional raytrace program (HARPO). Three dimensional rays were propagated both through the reconstructions and the original model. Travel time versus intensity (transmission loss) for the eigenrays was used as a basis for intercomparison. Tomographic results showed good reconstruction for a first iteration of the inversion, but inadequate vertical resolution. Iterations and the use of more refractive eigenrays are needed for improvement of the reconstruction, especially for the front. Reconstructed results for the acoustic field should improve conventional beamforming, but are probably inadequate for matched field processing. Theses. (edc)

Descriptors :   *ACOUSTIC FIELDS, *OCEAN MODELS, *GULF STREAM, *TOMOGRAPHY, UNDERWATER ACOUSTICS, ACOUSTIC REFRACTION, ACOUSTIC VELOCITY, BEAM FORMING, COMPUTER PROGRAMS, EDDIES(FLUID MECHANICS), ESTIMATES, FRONTS(OCEANOGRAPHY), INVERSION, ITERATIONS, LINEARITY, MATCHING, MATHEMATICAL MODELS, OCEAN SURFACE, OCEANOGRAPHIC DATA, OPTIMIZATION, PERTURBATIONS, MATHEMATICAL PREDICTION, DATA PROCESSING, RAY TRACING, RESOLUTION, STRUCTURAL PROPERTIES, SURFACE TEMPERATURE, THEORY, THESES, THREE DIMENSIONAL, TRANSMISSION LOSS, TRAVEL TIME, VERTICAL ORIENTATION

Subject Categories : Acoustics
      Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE