Abstract:

Carried out jointly by the Woods Hole Oceanographic Institution (WHOI), Naval Postgraduate School (NPS), Harvard University, and the University of Rhode Island (URI), the measurement program of an integrated acoustic-oceanographic field study called Shelfbreak PRIMER took place in the Middle Atlantic Bight. One of the goals of Shelfbreak PRIMER is to characterize and understand the propagation of sound from the continental slope to the continental shelf, including the effects of shelfbreak frontal processes, seasonal stratification, and topographic variations. The field work included two intensive 3-week experiments, one in July 1996 (summer) and the other one in February 1997 (winter). In particular, each of the two experiments employed a suite of acoustic and oceanographic sensors including several transceivers/sources and two vertical hydrophone arrays (VLAs) straddling the shelfbreak front and a SeaSoar that provided several high-resolution, three-dimensional surveys of the frontal region. The results from a data and modeling analysis of the pulse transmissions from a fixed sound source on the slope to a fixed VLA on the shelf are discussed. The objective of this analysis is to gain fundamental insights into the tidal-to-seasonal variability of the amplitudes and travel times of the strongly coupled normal modes. [Work supported by ONR.]