Long-term stability of a new conductivity-temperature sensor tested on the VENUS cabled observatory

The stability of the conductivity sensor is a key consideration for the long-term deployments of the instruments on mooring and observatories, because the conductivity measurement is very sensitive to the accumulation of organisms (bio-fouling) inside the sensor. We tested the performance of a conductivity sensor, the ALEC CTW, which features a simple but effective wiper mechanism to keep the sensing cavity of the conductivity cell free of bio-fouling. The sensor was deployed for a period of 12 months on the Victoria Experimental Network Under the Sea (VENUS) observatory, operated by the University of Victoria in British Columbia, Canada. The VENUS observatory provided power and data telemetry to monitor the sensor´s performance in real time. A post recovery calibration of the conductivity sensor showed that the wiper mechanism was effective in maintaining the sensors calibration.