REFERENCE CROP EVAPOTRANSPIRATION DETERMINED WITH A MODIFIED MAKKINK EQUATION

A modified version of the Makkink equation is shown to be a suitable a lternative for Penman's formula for the determination of the crop refe rence evapotranspiration E-ref that is used in the so-called crop fact or approach. Makkink's equation requires solar radiation and temperatu re data only. Since 1987 the Royal Netherlands Meteorological Institut e has calculated E-ref with the modified Makkink's formula on a routin e base. Using solar radiation derived from geostationary satellites, r emotely sensed estimates of crop reference evapotranspiration can be o btained. (C) 1998 John Wiley & Sons, Ltd.