Remotely sensed estimates of evaporation for irrigated cropsin northern Mexico

Hourly estimates of solar radiation were derived from satellite data for the Yaqui Valley in Mexico, made on a 50 km grid using the GEWEX/SRB algorithm applied with GOES-East data and, on a 4 km grid, using a high-resolution development of the algorithm with GOES-West data. On average, values derived from GOES-East are 18% greater, while those from GOES-West are 9% lower than field measurements. After re-calibration, random differences between hourly satellite estimates and surface observations remained. These were markedly reduced when daily-average values were compared. Root mean square error (RMSE) between the satellite and the surface measurements is lower for the high-resolution satellite estimates than it is for the low-resolution estimates, and there is a noticeable increase in apparent structure with the high-resolution data. Finally, the application of the high-resolution estimates of solar radiation to calculate daily estimates of crop evaporation for wheat and cotton fields is demonstrated.