Evapotranspiration
From Environmental Technology
In general, remote sensing techniques cannot measure evaporation or evapotranspiration (ET) directly. However, remote sensing does have two potentially very important roles in estimating evapotranspiration. First, remotely sensed measurements offer methods for extending point measurements or empirical relationships, such as the Thornthwaite [1948], Penman [1948] and Jensen-Haise [1963] methods, to much larger areas, including those areas where measured meteorological data may be sparse. Secondly, remotely sensed measurements may be used to measure variables in the energy and moisture balance models of ET. Although, there has been progress made in the direct remote sensing of the atmospheric parameters which affect ET, such as the Raman LIght Detection And Ranging (LIDAR), this is essentially a ground based, point measurement and will not be covered in this report.
