METRIC

The difference in these three terms represents the amount of energy absorbed during the conversion of liquid water to vapor, which is ET.

The surface energy balance is internally calibrated using ground-based reference ET that is based on local weather or gridded weather data sets to reduce computational biases inherent to remote sensing-based energy balance.

METRIC algorithms are designed for relatively routine application by trained engineers and other technical professionals who possess a familiarity with energy balance and basic radiation physics.

ET “maps” i.e., images via METRIC provide the means to quantify ET on a field-by-field basis in terms of both the rate and spatial distribution.

The use of surface energy balance can detect reduced ET caused by water shortage.In the decade since Idaho introduced METRIC, it has been adopted for use in Montana, California, New Mexico, Utah, Wyoming, Texas, Nebraska,[4] Colorado, Nevada, and Oregon.

The surface energy balance is used in many thermal-based remote sensing models to estimate ET. Rn is net radiation; H is sensible heat flux; G is heat conduction to the ground and ET is the amount of energy consumed by evapotranspiration (conversion of liquid water to vapor).