ENVIRONMENTAL PREDICTION RESEARCH FACILITY (NAVY) MONTEREY CALIF
As evaporation provides most of the feedback energy from the ocean to the atmosphere, it is imperative to know its distribution in time and space. Oceanic evaporation can only be computed with a Dalton type formula using necessary meteorological observations from voluntary observing and reporting vessels. The only parameter in this formula which can not be analyzed directly from ship observations is the water vapor pressure of the surface air. A formula for numerical computation of this parameter is given and briefly evaluated. Some monthly mean evaporation charts over the northern hemisphere are presented for selected months. The reasons for year-to-year differences and the anomalies of evaporation are briefly discussed, especially in relation to the surface wind patterns and in relation to the difference between the calculated water vapor pressure of the air and the saturation water vapor at the sea surface.