A deep sea temperature and pressure sensor for tidal measurement

Abstract

With ever increasing information being collected by the offshore continental shelf tide gauges, it became inevitable that researches into ocean tides would require instrumentation to collect tidal data in the deep oceans. This paper briefly describes the temperature and pressure sensors developed, and used by the Institute of Oceanographic Sciences (Wormley), in response to this requirement. Also described are the techniques and equipment used to calibrate these sensors. The deep sea tide gauges, each of which include two pressure and one temperature sensor, have now been operationally deployed on four occasions at pressures up to 300 bars (3000 m) providing well over 100 days of tidal data. In an international exercise to evaluate the performance of existing deep sea pressure sensors, results show that the unit described in this paper compares favourably with the other sensors. For example, the amplitude of the semi-diurnal components were within 1% of the average value, determined by all the sensors. The temperature sensor has an operational range within the limits — 1° and + 40°C and exhibiting a stability of the order 8 milli°C/month.