Deep ocean temperature profile measurements

Temperature is one of the most frequently measured parameters of the ocean because of its importance to the understanding and prediction of oceanic and meteorological events, and also because the measurement is required for the determination of salinity and density. The ocean temperature range is narrow,-2degto35degC, but measurement is complicated by the harsh ocean environment, the necessity of remote hands off readings, power limitations due to the cable, and the fast response required to obtain a profile in a reasonable length of time. Platinum and copper thermometers are used for most precision measurements with thermistors or thermocouples used in some cases to improve speed of response and for lesser accuracy. A number of very different circuits have been used successfully in salinity, temperature, and depth profiling systems and achieve millidegree accuracies in laboratory measurements. However, very careful precautions and many checks are required to achieve that accuracy in the field, and to achieve the correlation of conductivity, pressure, and temperature readings required for equivalent accuracy in the salinity and density measurements.