Direct calibration of in situ CTD´s

An interim report of the development of circulator equipment for direct calibration of conductive-cell-type in situ conductivity-temperature depth (CTD) instruments is given. Plugs containing thermistors are inserted in the ends of the cell and 200 cc samples of Copenhagen or other water are run through it from one reservoir to another. Laboratory results indicate that salinity accuracies within ±0.01⁰/₀₀ may be achieved routinely thus allowing direct comparison between the in situ reading and a bottle sample.