资源环境科技发展态势分析平台

Land evapotranspiration (ET), which involves the exchange of energy and water between the atmosphere and land, is dynamic and affects the spatiotemporal distribution of water resources, a key limiting factor in arid regions. The accurate quantification of ET and its two components, that is, soil evaporation (Es) and vegetation transpiration (Ev), is crucial for managing water resources to ensure sustainable development. However, estimating ET and its components is challenging due to limitations associated with the structure and parameterization of models. The three-temperature (3T) model, which includes limited inputs that are key to the ET process (e.g., net radiation and temperature), is hypothesized to be robust. In conjunction with the Heihe Watershed Allied Telemetry Experimental Research (HiWATER) project, this study was performed in a heterogeneous oasis in northwestern China using relatively high-density eddy covariance observations. The mean absolute percent error values of the ET and its components estimated with the 3T model from the field scale (flux observations as model inputs) to large scales (Fluke, Advanced Spaceborne Thermal Emission and Reflection Radiometer [ASTER] and Moderate Resolution Imaging Spectroradiometer [MODIS] data as model inputs) range from 9 to 25% over different landscapes. The ET estimates from the simple 3T model contained less bias than those from the Penman-Monteith equation, which requires more model inputs and parameterization. When the components were separated in the 3T model based on high-resolution images, such as Fluke and ASTER, the Ev/ET values were comparable to the isotope-based observations, and the mean absolute percent error values were <10%. With its limited inputs, the 3T model is able to simply and easily estimate ET and its components.