Provisional actual evapotranspiration (ETa) products derived from Landsat and weather data are now available for public download at a global extent for all Landsat data from 1984 onward. Landsat ETa is crucial for measuring water use and critical hydrologic components of the water budget for agricultural and natural landscapes at a higher spatial resolution. The U.S. Geological Survey (USGS) EROS Science Processing Architecture (ESPA) On Demand Interface provides higher-level science products derived from Landsat data. Actual evapotranspiration modeled with the Operational Simplified Surface Energy Balance (SSEBop) approach has been released as a Provisional Level-3 Science product for any Landsat image in the archive. This product utilizes Collection 2 Level 2 Landsat Surface Temperature data and improved parameterization and advancements in the SSEBop modeling approach to better estimate ETa regardless of land cover type, season, location, or time period. These products have been validated using in situ eddy covariance flux tower data and found to estimate ETa within 20% of the ground station ETa at daily time steps. Basin-scale evaluation of the SSEBop model over 1,000 watersheds in the conterminous United States has provided accuracies within 5% on an annual basis.
The EROS Center distributes the Landsat-based ETa to the public through the ESPA website. This service supplies land and water resource managers and researchers with an efficient, high-quality product without requiring the advanced knowledge in programming, remote sensing, or ET modeling necessary to create the product themselves. The dataset is provided at the overpass level (a single Landsat observation) and simply requires a list of the Landsat Collection 2 Level 2 Product IDs to place an order and initiate a download. The ETa product is useful for estimating field-scale consumptive water use that can be generated quickly and accurately to assess historical water use and plan water allocations to improve agricultural water management under a changing climate around the globe.
Provisional Landsat actual evapotranspiration (ETa) downloaded from the EROS Science Processing Architecture (ESPA) interface for four separate locations: a) Central Valley, California, USA; b) irrigated fields in Bahia, Brazil; c) the Nile River Delta, Egypt; and d) the Yangtze River, China. MODIS land cover ETa summaries show spatially averaged ETa (millimeters) for each land cover type. The associated manuscript is available here.
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