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Pegasus Data Information |
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Pegasus Data Information |
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Pegasus Operations
The Pegasus instrument is an acoustically-tracked, free-falling profiler of horizontal current components. The Pegasus instrument used by AOML consists of a hollow cylindrical metal tube with the electronics package sealed inside. A flotation collar attached to the exterior of the cylinder provides the instrument buoyancy. Pegasus houses a transducer/receiver, a thermistor sensor and a pressure sensor. When the Pegasus is in the water, it's transducer interrogates two fixed transponders on the ocean bottom at a frequency of 10 KHz at an interval of eight or sixteen seconds. Each transponder responds at a different frequency with the respective travel times, temperature and pressure recorded by the Pegasus. Each Pegasus station is defined by a unique geometry determined by positioning the bottom transponders prior to releasing the unit. A mean sound velocity profile for each station is used to convert the acoustic travel times from the transponders into ranges in meters. The baseline for estimates of speed becomes the base of a triangle, which is projected onto the bottom. The X and Y coordinates of the instrument at each pressure can then be determined from which the u- and v-velocity components are estimated. Additional details on the Pegasus operation are available in Spain et al. (1981), Leaman and Vertes (1983) and Leaman et al. (1987).
References
Leaman, K.D., R.L. Molinari and P.S. Vertes (1987) Structure and
variability of the Florida Current at 27N: April 1982-July 1984.
JOURNAL OF PHYSICAL OCEANOGRAPHY, 17, 565-583.
Spain, P.F., D.L. Dorson and H.T. Rossby (1981) PEGASUS: A simple
acoustically tracked velocity profiler. DEEP-SEA RESEARCH, 28A,
1553-1567.
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