Development of High Perfomance CTD sensor

Abstract

High performance CTD sensor for mooring system and profile measurement was developed. Circuit performance for realizing the target resolution (water temperature 0.0001 degC, conductivity 0.00001 S/m) was obtained by developing sensor signal processing method and circuit configuration. We developed a thermistor probe which has low depth dependence and a response time sufficiently short for profiling measurements. We also developed a conductivity sensor device of platinum electrode with high performance and repeatability. The new sensors have been calibrated and repeatedly tested in situ ((m-)TRITON buoy measurement and CTD castings) to improve the quality. As a result, the target performance (initial precision 0.002 degC, 0.0003 S/m, and time drift characteristics to withstand long-term mooring) comparable to SBE sensor (SBE37), was obtained.