Estimation of evapotranspiration using remotely sensed land surface temperature and the revised three-temperature model

Evapotranspiration (ET) is one of the most important land surface processes for terrestrial ecosystems because it strongly relates to both the energy balance and the mass balance of these ecosystems. Although there are many ground based approaches to estimate ET, it is still a challenge to estimate ET by remote sensing for most applications. The three-temperature model (3T model) is a recently developed approach used to estimate ET based on ground measurement. Compared with other conventional ET estimation algorithms, fewer input parameters are required in the 3T model. Therefore, it shows good potential for remote sensing application. In this study, we aimed to extend the 3T model for remote sensing application and to validate its accuracy. First, algorithms to extend the 3T model for estimating the regional ET of mixed landscapes were proposed. Then, two case studies were presented using Landsat Thematic Mapper (TM)/Landsat Enhanced Thematic Mapper Plus (ETM+) images. Thereafter, the Bowen ratio energy balance method (BREBM) and the residual method of the energy balance equation (RMEBE) were adopted to validate the performance of the revised 3T model. Results showed that the absolute error of the mean daily ET estimated by the BREBM and the revised 3T model was 0.23 mm d−1, whereas between the RMEBE and the revised 3T model it was 0.07 mm d−1. This accuracy is acceptable for most application purposes. The revised 3T model demonstrates the ability to remotely sense actual regional evapotranspiration.