2007 Volume 5 Pages 31-39
Temperature and conductivity sensors manufactured by Sea Bird Electronics, Inc. (SBE) are affixed to APEX-type Argo floats manufactured by Webb Research Co. Before shipping to users, calibration of the sensors is carefully carried out at SBE. However, the sensors are recalibrated at Japan Marine-Earth Science and Technology Agency (JAMSTEC) to reconfirm sensor accuracy considering a long transportation from SBE and quite a long storage time at JAMSTCE before deployment. In this paper, we describe and analyze these recalibration results. We used the same calibration technique as used by SBE, comparing outputs of temperature and conductivity sensors with those of highly quality-controlled standard temperature and conductivity sensors. We set thresholds of good or bad temperature and conductivity (salinity) sensors to be ± 0.0050 ℃ and ± 0.010 psu, respectively. The thresholds are selected to meet the target of the Argo project. Between 2001 and 2005, 228 sensors which are about 60 % of all were recalibrated at JAMSTEC. All the temperature sensors fall within the threshold. Of the conductivity sensors, 175 (77%) passed at the first measurement of recalibration series, while 30 (13%) passed after two or more measurements. The latter sensors were carefully cleaned to remove contaminations by dust or chemical pollutants. However, nine sensors (4%) did not pass recalibration test and were returned to SBE for further checking and repairs.
