Abstract:

The shelf edge studies acoustic measurement experiments (SESAME) were performed in the North West Approaches to the British Isles. The SESAME experiments were a collaborative effort between the Natural Environment Research Council, the Defence Research Agency (both of the United Kingdom), and the Naval Research Laboratory (Stennis Space Center). The objective of the experiments was to determine the effects of internal waves formed at the shelf edge on acoustic propagation. Oceanographic measurements were gathered continuously over an 18-month period and acoustic experiments were performed during the summers of 1995 and 1996. Measurements of temperature, conductivity, and current were made within the water column, sediment cores were taken of the ocean bottom, and SAR images of the sea surface were taken of the experimental area. Range and time-varying acoustic experiments were performed in the along shelf and cross shelf directions over a frequency band of 100--2100 Hz. Both narrow- and broadband (frequency modulated) signals were transmitted. A review of the two experiments and some of the oceanographic and acoustic data collected will be presented. [Work supported by ONR and NRL.]