Abstract :
The Profiling Oceanographic Sensor measures the temperature profile in the upper 300m of the water column. The sensor body, containing a platinum resistance thermometer, strain gage pressure transducer and associated signal conditioning circuitry, free-falls from the sea surface at a near constant rate until reaching the maximum sensing depth. During free fall, the sensor drops at approximately 2.5m/s and data are sent in digital form to the surface via an electromechanical cable. Temperature and pressure data are sampled and digitized 52.5 times per second, equivalent to one data sample for each 4 cm of drop. Data resolution is 0.03 degrees C and 33 millibars for temperature and pressure, respectively. A winch of unique design is used to deploy and retrieve the sensor. The winch consists of an articulated spool which rotates to a vertical position during sensor deployment, allowing the cable to freely play out as the sensor falls. This technique effectively decouples the falling sensor from any surface motions at the winch support. For retrieval, the spool is rotated to a horizontal position and is driven by an electric motor for rewinding the sensor cable. Results of at-sea testing are presented. Included in the results are temperature profiles obtained under unattended operating conditions aboard a data buoy 800 miles north of Hawaii.
Keywords :
ocean temperature; oceanographic equipment; oceanographic techniques; pressure sensors; thermometers; articulated spool; depth 300 m; electromechanical cable; maximum sensing depth; platinum resistance thermometer; pressure data; profiling oceanographic sensor; sensor body; sensor cable; signal conditioning circuitry; strain gage pressure transducer; temperature data; temperature profile; winch; Capacitive sensors; Electric motors; Mechanical cables; Mechanical sensors; Ocean temperature; Sea measurements; Sea surface; Temperature measurement; Temperature sensors; Winches;
