Comparison of Three Remote Sensing Based Multi-Source Evapotranspiration Models

Evapotranspiration (ET) links the energy, water and carbon cycles from local to global scales. Several remote sensing (RS) based models, with varying complexity and underlying physical concepts have been developed. Some of these models estimate total ET and some can partition ET into its constituent components. This study aims to compare three multi-source ET models, Priestley-Taylor-Jet Propulsion Lab (PT-JPL), Soil Plant Atmosphere and Remote Sensing Evapotranspiration (SPARSE) and Surface Temperature Initiated Closure (STIC) for their performance in simulating total ET and its components over four sites. The PT-JPL, SPARSE (layer), SPARSE (patch) and STIC models exhibited RMSE of 89.68, 57.3, 61.67 and 96.43 W m^-2 respectively for the four sites taken together at half hourly time scales. In addition to differences in total ET simulated by the models, there was a remarkable difference between them in simulating the E and T components too. This clearly suggests that care must be taken when using these models to simulate ET and its components.