ASA 126th Meeting Denver 1993 October 4-8

2aAO6. Modal inversion for bottom sound-speed profile in shallow Arctic waters using broadband signals.

T. C. Yang

Naval Res. Lab., Washington, DC 20375

T. Yates

Vector Res. Co., Rockville, MD 20852

Acoustic inversion of geoacoustic properties in the ocean bottom has been investigated recently using matched-field processing. In the shallow Arctic waters, the acoustic signal may still be dominated by waterborne modes. As a consequence, the matched-field correlation may not be very sensitive to bottom sound-speed variation. It is found that in a water depth of approximately 600 m the matched-field correlation remains very high (>0.95) even with a mismatch of 50 m/s in bottom sound-speed profile. To improve the sensitivity to bottom mismatch, we include only the high-order modes in the matched-field/mode correlation. This method is investigated using a simulated broadband signal and also using SUS data received on a vertical array. The source is localized using broadband matched-field/mode processing. Short-range data are considered to maximize bottom interacting signals.