ITRC uses a modified Mapping of EvapoTranspiration with Internal Calibration (METRICTM) procedure to compute actual evapotranspiration using LandSAT Thematic Mapper data. The original METRIC procedure was developed by Dr. Richard Allen (University of Idaho). ITRC has made a number of modifications to the original procedures including using a grass reference evapotranspiration instead of alfalfa, a semi-automated calibration procedure, spatially interpolated ETo, modifications to the aerodynamic resistance and albedo computations for certain crops, etc.



Remote Sensing of Evapotranspiration Using the ITRC-METRIC Procedure

The ITRC-METRIC process is based on a surface energy balance and includes corrections for aerodynamic resistance. It depends upon both accurate and frequent LandSAT satellite thermal images and understanding of the cropping systems within a region. The METRIC programs have gradually evolved from research in the US and other countries with the objective of being able to directly estimate actual ET over large areas with limited data availability (such as crop type, irrigation method, irrigation practices, etc.).


Click on the image to the right for a visual summary of the technique.

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