Paul A. Baxley
Ocean and Atmospheric Sciences Div., Acoust. Branch, NCCOSC RDTE Div. Code 541, 53560 Hull St., San Diego, CA 92152-5001
Newell O. Booth
NCCOSC RDTE Div., San Diego, CA 92152-5001
Matched-field replica models based on an inaccurate knowledge of
geoacoustic parameters such as bottom attenuation, shear, and interfacial
sound-speed discontinuities, can predict an incorrect number of propagating
modes for a shallow-water channel. The resulting degradation in the
matched-field ambiguity surface can be substantially reduced by optimizing over
the modal-sum-limit used in the replica model. The use of this technique for
multitone (70, 95, 145, and 195 Hz) source-tow data recorded near San Diego
during the first shallow water evaluation cell experiment (SWellEX-1)
significantly increased matched-field correlation levels for all narrow-band
tones (and their average), with the maximum peak more frequently coinciding the
correct source location than that observed with a previous nonoptimized model
[Schey and Ryan,