Matched-field processing in a wedgelike ocean

The neglect of the three-dimensional nature of acoustic propagation in a wedgelike shallow-water ocean can cause significant localization errors in underwater acoustic array processors. This study examines in detail the effect of such neglect on the performance of matched-field processors in wedgelike environments, along with an analysis of the performance improvement gained by including known three-dimensional effects into the processor. Results were obtained via computer simulations of signals received on a vertical line array (VLA) from a source moving in the cross-slope direction relative to the ASA benchmark penetrable wedge. Typical effects observed when the three-dimensional nature of the propagation was ignored include an increase in the range error as the source moves away from the VLA (giving the impression of an accelerating source), distinct jumps to incorrect depths as modes are stripped, and loss of signals upon entering a horizontal shadow zone (all modes stripped). Incorporation of the known three-dimensional propagation into the processor not only eliminates the localization errors but provides azimuthal discrimination. Recent progress has also been made in the computer simulation and data analysis of a real wedge-shaped environment off San Clemente Island near San Diego. [Work supported by ONR/NRaD.]