Development of a Deep-Towed Array Geophysical System: A New Capability for Deep-Ocean Acoustic Measurements

摘要

Development of a deep-towed seismic profiling system has been completed after four years of design, fabrication, and testing. This system provides the capability to determine the detailed acoustic character of the sea floor and upper 500-1000 m of subbottom structure. The system is designed for tow depths of 6000 m while operating at an altitude of 100 m above the sea floor. The major components of the system include: a sound source located in the deep-towed vehicle, which operates over a frequency range from 260 Hz to 650 Hz at a peak source level of 201 dB re 1 micropascal at 1 m; a 24 channel, 1000 m long array attached as a tail to the deep-towed vehicle; a duplex digital telemetry link to communicate with the deep-towed system over a coaxial tow cable; a digital data record system; a real time engineering data display system; a short baseline navigation system; handling hardware to deploy and retrieve the system; and two instrumentation vans to support system operations. This paper discusses the unique hardware developed for the deep-towed seismic system and focuses on the acoustic subsystems. Also reviewed is a performance prediction analysis initially performed to define geoacoustic parameter measurement improvements achievable with a deep-towed configuration. Field measurement engineering results acquired during the system's final performance evaluation are presented. Data was acquired at two depths of 4500 m. Keywords: Acoustics; Seismic profiling; Deep-ocean measurements.