Estimating quality of indirect measurements of sea water sound velocity by CTD data

The publication presents the results of calculations of the uncertainty estimates for indirect measurements of the sound velocity using CTD data. The sound velocity dependence on the input parameters was analyzed. The input parameters include absolute salinity, temperature and hydrostatic pressure. The diagrams of the sensitivity coefficients of the dependence of the sound velocity on the input parameters are constructed, which are applicable for practical calculations. For various classes of measurement instruments the diagrams of the measurement uncertainty components on each of three input parameters and the diagram of the combined standard uncertainty of the indirect measurements of the sound velocity were calculated. The uncertainty estimate diagrams for the sound velocity measurement in the sea water can be used in oceanography investigations and for the work of metrological laboratories. The authors defined the potential applications of CTD probes with various precision for the indirect measurements of sound velocity.