An optical trapezoid model for actual evapotranspiration and winter wheat yield estimation

Abstract

In this study, a satellite-based actual evapotranspiration (ETa) estimation model, OPTRAM-ET, based on the optical trapezoid model (OPTRAM) estimates of soil moisture and a vegetation index (VI) was introduced and its application for crop yield estimation using a light use efficiency (LUE) model was assessed. The OPTRAM-ET model was applied to Sentinel-2 and evaluated against ETa estimates of 8 eddy covariance towers in the south of Germany. The proposed model showed promising performance with RMSE of 0.82 mm/day. In addition, its performance for winter wheat yield estimation was satisfactory with R2 of 0.46 and RMSE of 2.77 t/ha. This model allowed for ETa and crop yield maps with increased spatial resolution compared with thermal-based methods.