Analysis of acoustic propagation in the region of a shelfbreak front

Abstract

The 1996-97 Shelfbreak Primer Experiments, which involved extensive oceanographic and acoustic measurements, have provided a large dataset with which to investigate the complexities of acoustic propagation in a shelfbreak front region. This paper looks in detail at a subset of the acoustic transmissions extending over a 12-day period during the summer 1996 experiment. Acoustic propagation near the continental shelfbreak is affected by numerous aspects of the oceanography, including but not limited to variable bathymetry, the shelfbreak front, an energetic soliton field, and interactions with occasional Gulf Stream filaments. Because of strong internal wave-induced coupling between the acoustic modes, changes in the large-scale oceanography, such as movement of the front, are difficult to distinguish. The impact of the soliton field on the acoustics is investigated, particularly from the perspective of wanting to invert for the front and other mesoscale features in the presence of this noise. One measure of oceanographic interest is the horizontal wave-number spectrum for the shelfbreak region. The possibility of obtaining this oceanographic quantity from acoustic data is considered. [Work supported by ONR.]