Evaporation Minus Precipitation (E-P)

Evaporation minus precipitation (E-P) is the net freshwater flux at the ocean surface, the difference between water lost to the atmosphere by evaporation and gained by rainfall, usually expressed in millimeters per day or meters per year. Positive E-P (net evaporation) increases sea surface salinity and characterizes the subtropics; negative E-P (net precipitation) freshens the surface and dominates the tropical rain belt and high latitudes. E-P drives the surface limb of the global water cycle and the salinity pattern that ocean salinity now acts as a rain gauge for. The latent heat flux and E share the same evaporation rate through the latent heat of vaporization.