Numerical Studies of Acoustic Particle Velocity and Acoustic Variability with a SSF/PE Model

Abstract

The calculation of underwater acoustic pressure fields using numerical models has been at the core of numerous projects related to both sonar and environmental applications. This varies from simple sonar "range-of-the-day" predictions to the inversion of acoustic data for determination of bottom ocean properties. Although great progress has been made with existing models that compute the acoustic pressure field, much of the previous work has ignored other aspects of the propagation, such as the additional information available in the associated acoustic particle velocity fields, and the impact of environmental uncertainty on sonar predictions. The goal of this 2-year project was to examine these issues and determine how they may be utilized to improve performance for a variety of applications. OBJECTIVES The objectives met for the first year's effort were to expand existing modeling capabilities to (1) provide calculations of the unique characteristics of the acoustic particle velocity field, (2) directly compare this with analytical predictions, (3) examine the field behavior in range-dependent environments, and (4) investigate properties of the vector fields on basic signal processing algorithms. Calculations of acoustic particle velocity were made in generic ocean environments in an attempt to understand what features of the particle velocity field may be unique and exploitable. By developing intuition on the nature of the velocity field, new algorithms for array processing and exploitation of environmental variability were developed.