FY 1978

A shallow water pressure-temperature gage (PTG): Design, calibration and operation

Hayes, S.P., J. Glenn, and N. Soreide

NOAA Tech. Memo. ERL PMEL-12, NTIS: PB-286754/7, 35 pp (1978)

An internally recording, low power instrument to measure water pressure and temperature in water depths of up to 250 m is described; calibration and processing techniques are discussed; some field results are presented. The gage uses a quartz crystal pressure transducer, an epoxy-coated thermistor, and a commercially available digital recording system. Calibration results show a temperature dependence which can amount to 1 mb/°C for some gages at some pressures. This is a combined effect due to the temperature dependence of the clock and of the pressure transducer. Long-term drift of the pressure transducer could not be accurately assessed by the laboratory tests, but appeared to be roughly of the same magnitude as the manufacturer's specification for the transducer. Results from deployments in the Gulf of Alaska showed six month records which had trends of less than 1 cm/mo. Much of this trend could be oceanic.