Actual Evapotranspiration at Landsat scale at CONUS scale for 2010-2019

The estimation and mapping of actual evapotranspiration (ETa) is an active area of applied research in the fields of agriculture and water resources. Thermal remote sensing-based methods, using coarse resolution satellites, have been successful at estimating ETa over the conterminous United States (CONUS) and other regions of the world. In this study, we present CONUS-wide ETa from Landsat thermal imagery-using the Operational Simplified Surface Energy Balance (SSEBop) model in the Google Earth Engine (GEE) cloud computing platform. Over 150,000 Landsat satellite images were used to produce 10 years of annual ETa (2010-2019). The accuracy assessment of the SSEBop results included point-based evaluation using monthly Eddy Covariance (EC) data from 25 AmeriFlux stations as well as basin-scale comparison with annual Water Balance ETa (WBET) using more than 1,000 sub-basins. The WBET evaluation indicated that the SSEBop model is strong in explaining the spatial variability (up to R2 > 0.9) of ETa across large basins, but it also identified broad hydro- climatic regions where the SSEBop ET showed directional biases, requiring region-specific model parameter improvement and/or bias correction. Annual ETa anomalies over the 10-year period captured widely reported drought-affected regions, for the most part, in different parts of the CONUS, indicating their potential application in the mapping of regional- and field-scale drought and fire impacts.