A simple model to estimate the daily value of the regional maximum evapotranspiration from satellite temperature and albedo images

Abstract

We have tried an adaptation of the radiation model proposed by FAO, applicable in any area, for the estimation of the regional maximum evapotranspiration, ET, from temperature and albedo images obtained from a satellite. This model is based on the relationships ET_m = k _cET_o ET_o = A + BR _g + CR _g T_a ^max where k _c is the crop coefficient, ET_o is the maximum evapotranspiration of the reference crop (green grass), R_g is the global radiation obtained from satellite albedo images, T _a ^max is the maximum temperature of the air obtained from the near-midday satellite temperature and A, B and C are the empirical coefficients characteristic of each zone calculated for different intervals of wind velocity and relative humidity of the air. By applying this model to the Valentian Region (Spain) we have obtained an estimation of the maximum daily evapotranspiration to an accuracy of 20 per cent.