Science Meetings

Thermodynamic Salinometry
Shkvorets, I. (26-Feb-14)

Internationally adopted as standard method of salinometry, the Autosal technique has been utilized for more than 30 years. However, limitations of the Autosal temperature setting at room temperature creates a discrepancy between the conductivity of the seawater measured by a CTD and by the Autosal. In this paper I propose a complementary method for onboard salinity measurements. Using an inductive dual cell ratiometric salinometer MS-315e (developed by RBR Ltd.) - in a water bath set to the temperature of the deep-waters, an operator can perform direct samples salinity measurements, without waiting for the sample warming to attain laboratory temperature. This method of the "thermodynamic salinometry" not only provides fast CTD cast data validation, but also serves as a more sophisticated method of practical salinity measurements without loss of the original physical-chemical composition of the seawater samples. Testing of this method in the Atlantic and Pacific waters shows considerable differences in value of the practical salinity in comparison to standard method. What is also important, the MS-315e design provides measurement of the conductivity ratio of any natural saltwater sample in a dynamic temperature range. Measured differences in Rt can be used as correction for eliminating the effect of non-ideal compositions of natural seawater and harmonizing the PSS-78 for a variety of natural waters.