Marshall H. Orr
Acoust. Div., Naval Res. Lab., Washington, DC 20375-5000
James F. Lynch
Woods Hole Oceanogr. Inst., Woods Hole, MA 02543
The range-dependent properties of a variety of pulsed acoustic signals (200--1000 Hz) propagating in a shallow water waveguide (New Jersey shelf, July--Aug. 1995) randomized by internal waves, bottom heterogeneity and surface roughness have been measured during a 27-day interinstitutional experiment. A 40-km acoustic propagation path located along the NSF Ocean Drilling Program seismic line 1003 was instrumented with moored acoustic sources, three moored acoustic vertical line arrays; eight moored thermistor strings; two moored ADCPs; and two surface gravity wave spectrum buoys. The ocean surface was imaged with ship, P-3 aircraft and ERS-1 radars. The water volume was imaged with high-frequency acoustic systems. Water properties were also measured with shipborne ADCP and CTD sensors. Acoustic sources and receiving arrays were positioned with DGPS and acoustic navigation systems. Timing was maintained with Rubidium clocks. The theoretical/experimental rationale for this experiment will be outlined. The anticipated effects of internal wave- and seafloor-induced randomness on the range-dependent properties of the acoustic signals will be summarized. Preliminary results of the measurements will be presented. [Work supported by ONR.]