Accession Number:

ADA470379

Title:

Geoacoustic Inversion by Mode Amplitude Perturbation

Descriptive Note:

Doctoral thesis

Corporate Author:

WOODS HOLE OCEANOGRAPHIC INSTITUTION MA

Personal Author(s):

Report Date:

2007-02-01

Pagination or Media Count:

129.0

Abstract:

This thesis introduces an algorithm for inverting for the geoacoustic properties of the seafloor in shallow water. The input data required by the algorithm are estimates of the amplitudes of the normal modes excited by a low-frequency pure-tone sound source, and estimates of the water column sound speed profiles at the source and receiver positions. The algorithm makes use of perturbation results, and computes the small correction to an estimated background profile that is necessary to reproduce the measured mode amplitudes. Range-dependent waveguide properties can be inverted for so long as they vary slowly enough in range that the adiabatic approximation is valid. The thesis also presents an estimator which can be used to obtain the input data for the inversion algorithm from pressure measurements made on a vertical line array VLA. The estimator is an Extended Kalman Filter EKF, which treats the mode amplitudes and eigenvalues as state variables. Numerous synthetic and real-data examples of both the inversion algorithm and the EKF estimator are provided. The inversion algorithm is similar to eigenvalue perturbation methods, and the thesis also presents a combination mode amplitudeeigenvalue inversion algorithm, which combines the advantages of the two techniques.

Subject Categories:

  • Geology, Geochemistry and Mineralogy
  • Numerical Mathematics
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE