Retrieval of evapotranspiration over the Alpilles/ReSeDA experimental site using airborne POLDER sensor and a thermal camera

Knowledge of land surface evapotranspiration is of prime interest for environmental applications, such as optimizing irrigation water use, especially in arid and semiarid rangelands where water shortage is a critical problem. Numerous methods aiming at estimating evapotranspiration have been proposed in the literature. In the current paper, we assess the potential of the evaporative fraction based on the S-SEBI (Simplified Surface Energy Balance Index) concept for estimating instantaneous evapotranspiration, and extend this potential to the retrieval of daily evapotranspiration (ETd). To this end, a feasible and operational method is developed, which allows mapping instantaneous and daily evapotranspiration over the Alpilles ReSeDA (Remote Sensing Data Assimilation) experimental area. The method is implemented using data collected with two airborne sensors: PolDER (Polarization and Directionality of Earth Reflectance) and a Thermal camera. The validation over test sites shows that daily evapotranspiration can be obtained within an error of 1 mmd− 1. Finally a daily evapotranspiration image for the Alpilles ReSeDA experimental site is presented.