<scp>TEOS10</scp> compliant salinity and density equations for sound speed instruments

Abstract TEOS‐10 compliant equations are presented for the direct calculation of salinity, density, and Sigma0 from triplets of temperature, pressure, and sound speed for marine and estuarine waters. The 73, 71, and 71 term, respectively, 6 th ‐order equations, are valid over an environmental range of 0–40°C in situ temperature, 0–6000 dBar pressure, and 0–40 practical salinity. The equations can reproduce a TEOS‐10 speed of sound equation–derived reference parameter space to a root mean square (RMS) error of ± 0.002383 g kg −1 , ± 0.002814 kg m −3 , and ± 0.002812 kg m −3 , respectively. The limitation for practical use is the order ± 0.05 m s −1 accuracy of the TEOS‐10 equation for calculating sound speed. Four new in situ reference datasets are subsequently used to improve on this limitation. Adding the reference datasets leads to 70, 72, and 72 term, respectively, 6 th ‐order equations, to an overall RMS error of ± 0.012251 g kg −1 , ± 0.010023 kg m −3 , and ± 0.010209 kg m −3 , and extends the temperature validity range to −1.772 to 40.000°C in situ temperature.