Combination of temperature and salinity

Water masses have characteristic temperature-salinity values (see accompanying figure east of South Africa: TSW= Tropical Surface Water; STSW = subtropical surface water; CW=Central Water; RSW=Red Sea Water; AAIW= Antarctic Intermediate Water). Using a graph like this, researchers can take a sample of sea water and trace its origin to the various water masses. The figures in brackets are depths in metres where the particular water masses are encountered.