Advection Modification of the Priestley and Taylor Evapotranspiration Formula¹

Abstract

Abstract The empirical formula of Priestly and Taylor (1972) relating the evapotranspiration from a well‐watered surface to the net radiation and a function of the air temperature is modified to include a saturation deficit term to account for high local advection. The model is tested on two seasons of daily evapotranspiration measurements over irrigated potatoes ( Solarium tuberosum L.), resulting in good agreement and a substantial improvement over the unmodified formula. Alfalfa ( Medicago saliva L.) measurements are also represented well by the model, but no better than by the Priestley‐Taylor formula calibrated during a period of high advection.