The results of the correlation coefficient r computation, between temperature T and salinity S on the standard sea surfaces are reported. The coefficient r appears to be a good index revealing the phenomena of sinking surface water, made denser by intensive cooling and evaporation. This is clearly seen through the elaboration: of the I.G.Y. 1957-58 measurements in the central South Tyrrhenian Sea, of the "Meteor" (1925-27) in the Atlantic, and for the NORPAC 1955 in the Pacific Ocean.