Interrelations between processes of radiation, convection, and evaporation near the sea surface are determined quantitatively, for the North P acific Ocean. The object was to investigate these processes of heat changes as a whole rather than to consider any one of them in detail. In particular, revised values of a coefficient giving the time rate of temperature change were determined for use in a method of calculating surface currents from temperature. Observations of a twenty-year series of North Pacific Ocean surface temperatures in an eastern area extending from latitude 20° to 50° were selected so as to be least influenced by ocean currents....