The specific gravity/salinity/temperature relationship in natural sea water

Abstract Specific gravities, relative to an isotopically defined pure water at 4°C, have been determined on natural sea waters covering the salinity range 9–41% at temperatures of 0–25°C. A mathematical expression has been computed for the relationship between specific gravity, salinity and temperature. Except in the low salinity region the results agree well with those of Forch, Knudsen and Sorensen (1902) on which the present Hydrographical Tables are based but indicate that these tables are low by an average of 0·006 in sigma- t .