Abstract:

Simultaneous observations of internal wave activity and acoustic wave propagation in 70-m water in the Yellow Sea were made in the late summer of 1996. The primary objective of this experiment was to validate the predicated modal coupling and fluctuations induced by shallow-water internal waves. The Yellow Sea provides an ideal environment for such research because it has a very flat and homogeneous bottom and a very strong, sharp thermocline. The environment lends itself to relatively simple models for both the acoustic field and the internal wave field. Propagation was measured over distances up to 55 km in the frequency range of 50 Hz--5 kHz. The receivers were three moored and two suspended hydrophone arrays. Internal wave activity was monitored using thermistor chains, SAR satellite imagery, and high-frequency sonar. Propagation data were taken as a function of range, as a function of time at a fixed range, and as a function of azimuth in the presence of differing levels of internal wave activity. Supporting environmental data obtained during the experiment include ADCP, bottom profile and surface wave-height spectra, and bottom coring. Preliminary data on internal wave field, sound propagation, reverberation, and bottom acoustic parameters will be presented. [Work supported by ONR and the Chinese Academy of Sciences.]