Laboratory evaluation and preliminary field trials of new “WOCE standard” Idronaut MK317 and OS316 CTD probes

The MK 317 is a multi-parameter conductivity, temperature and depth profiling unit (CTD) with a fast (50 mS) platinum resistance thermometer and a free flushing 3 cm ceramic, four electrode, conductivity cell. As used in the Neil Brown instrument Systems, Inc. MKIII CTD one of the units tested had redundant temperature and conductivity probes installed. Laboratory evaluations including shock tests on the pressure sensor, and both noise and calibration stability tests on conductivity and temperature sensors have been conducted at the SACLANT Underwater Research Center, oceanographic calibration facility. This facility has for three decades generated CTD calibrations that exceed WOCE standards in order to satisfy both NATO Navies and the Southern European Oceanographic Research community requirements. Results are presented and compared from casts made with both the Mk 317 and OS 316 (in self recording mode) and SBE 911 plus or SBE 25 operating from the same deployment frame