Operational aspects of satellite-based energy balance models for irrigated crops in the semi-arid U.S.

SEBAL and METRIC remote sensing energy-balance based evapotranspiration (ET) models have been applied in the western United States. ET predicted by the models was compared to lysimeter-measured ET in agricultural settings. The ET comparison studies showed that the ET estimated by the remote sensing models corresponded well with lysimeter-measured ET for agricultural crops in the semi-arid climates. Sensitivity analyses on impacts of atmospheric correction for surface temperature and albedo showed that the internal calibration procedures incorporated in the models helped compensate for errors in temperature and albedo estimation. A repeatability test by two totally independent model applications using different images, operators and weather datasets showed that seasonal estimations by the models have high repeatability (i.e. stable results over ranges in satellite image timing, operator preferences and weather datasets). These results imply that the SEBAL/METRIC remote sensing models have a high potential for successful ET estimation in the semi-arid United States.