Salinity
D1. Physical and chemical oceanography and marine meteorologyDefinition
Concentration of dissolved salts in seawater, dimensionless on PSS-78.
Salinity is the concentration of dissolved salts in seawater. Modern Practical Salinity (PSS-78) is dimensionless and derived from the conductivity ratio of a sample to a standard KCl solution; open-ocean values cluster near 35. TEOS-10 introduced Absolute Salinity (grams per kilogram) for thermodynamic accuracy. Salinity, with temperature and pressure, sets density and so drives the thermohaline circulation and water-mass formation.