ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

4aAB7. Three-dimensional localization of a blue whale using broadband matched-field processing for range and depth, and plane-wave adaptive beamforming for azimuth.

G. L. D

W. A. Kuperman

W. S. Hodgkiss

L. F. Berger

Marine Phys. Lab., Scripps Inst. of Oceanogr., San Diego, CA 92152-6400

During a recent shallow water experiment conducted 10--15 km west of San Diego, blue whale calls were recorded simultaneously on two underwater hydrophone arrays, an 18-element, 205-m-aperture horizontal line array, and a 64-element, 115-m-aperture vertical line array. These data are used to localize the calling whale in 3-D space and then to make estimates of its source level. First, adaptive plane-wave beamforming is used with the horizontal line array data to obtain finely resolved bearing estimates. Then, the bottom bathymetry profiles along these bearing estimates are used as input to a 2-D full-wave-field normal mode code (written by Mike Porter) for generating ``replica vectors'' (i.e., predictions of the acoustic field) received by the vertical line array. A search in range and depth for the best match between the replica vectors and the actual field measured by the vertical array (``matched-field processing'') then is performed to obtain the best-fit position of the whale in 3-D space. Finally, estimates of the source level of the whale calls are made. [Work partially supported by ONR, Code 321.]