Evapotranspiration Estimates from Surface Energy Balance Compared Against Eddy Covariance, Surface Renewal, Water Balance and Crop Coefficient Method.

California Actual Evapotranspiration (CalETa) Mapping program generates statewide daily ETa dataset at 30-meter resolution. CalETa is the result of a robust and efficient framework that relies on publically available satellite earth observation data, local meteorological data, and open source algorithms. The core of the framework uses the Surface Energy Balance System (SEBS) algorithm. With more than 200 crops grown and a terrain covered with valleys, plains, coasts and mountains; validation becomes a massive task. The objective here was to acquire all available observed dataset and compare it with CalETa dataset. The following dataset were used for the performance analysis:

1. Eddy covariance data from Ameriflux Stations
2. Eddy covariance data from Rice field
3. Scaled down version of Surface Renewal observations from Pistachio Orchards
4. Eddy Covariance data from groundwater dependent native ecosystem
5. Water Balance estimates from CalSIMETAW model
6. Crop Coefficient method for estimating of crop evapotranspiration

Results show good performance of CalETa under different landscape conditions. Measurement and estimation techniques, time and space integration of data, and several other factor influence the validation analysis hence performance assessment cannot be absolute. CalETa is a consistent, validated, transparent, and accessible dataset, which has considerably improved the modeling inputs and is being widely used as a water management tool in statewide water planning efforts.