Practical Salinity Scale 1978 (PSS-78)

The Practical Salinity Scale 1978 defines salinity from the electrical conductivity ratio of a seawater sample to a reference potassium chloride solution at fixed temperature and pressure. It is dimensionless (a value near 35 means about 35 grams of salt per kilogram) and made salinity a precise, reproducible CTD measurement rather than a chemical titration. TEOS-10 retains PSS-78 conductivity-based salinity as the measured input from which Absolute Salinity is computed.