Accession Number:

ADA629655

Title:

Modal Mapping in a Complex Shallow Water Environment

Descriptive Note:

Corporate Author:

WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF APPLIED OCEAN PHYSICS AND ENGINEERING

Personal Author(s):

Report Date:

1999-09-30

Pagination or Media Count:

4.0

Abstract:

LONG-TERM GOALS. The long-term goal of this research is to increase our understanding of shallow water acoustic propagation and its relationship to the three-dimensionally varying geoacoustic properties of the seabed. OBJECTIVES. The scientific objectives of this research are 1 to develop high-resolution methods for characterizing the spatial and temporal behavior of the normal mode field in shallow water 2 to use this characterization as input data to inversion techniques for inferring the acoustic properties of the shallow water waveguide and 3 to use this characterization to improve our ability to localize and track sources. APPROACH. An experimental technique is being developed for mapping the wavenumber spectrum of the normal mode field as a function of position in a complex, shallow water waveguide environment whose acoustic properties vary in three spatial dimensions. By describing the spatially varying spectral content of the modal field, the method provides a direct measure of the propagation characteristics of the waveguide. The resulting model maps can also be used as input data to inverse techniques for obtaining the acoustic properties of the waveguide. The experimental configuration consists of a fixed source radiating one or more pure tones to a field of freely drifting buoys, each containing a hydrophone, GPS navigation, and radio telemetry. In this context, two-dimensional modal maps in range and azimuth, as well as three-dimensional bottom inversion in range, depth, and azimuth, become achievable goals.

Subject Categories:

  • Physical and Dynamic Oceanography
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE