The USGS developed the Simplified Surface Energy Balance (SSEB) model to estimate landscape ET for various applications. Since ET is a critical component of the hydrologic cycle and the most difficult to measure, remote sensing-based techniques such as the SSEB have become very important. For early warning applications, ET provides information on crop performance and drought monitoring. For hydrological applications, ET is used to estimate groundwater recharge and withdrawal rates. Water management personnel use ET information for estimating irrigation water use and need.
The SSEB ET model was run using a combination of moderate-resolution imaging spectroradiometer data sets (land surface temperature, normalized difference vegetation index, and albedo) and weather data sets such as radiation, air temperature, wind speed, relative humidity and air pressure, for the continental U.S. and Africa. The severity and extent of the drought in the southern Great Plains is depicted below.
Seasonal ET anomaly for the 2011 year (April-September). Note the severity and extent of the drought in the southern Great Plains.