Development of an evapotranspiration index from Aqua/MODIS for monitoring surface moisture status

Terrestrial evapotranspiration is a critical process for the energy and hydrologic partitioning at the land surface. We have developed an estimation method of the evaporation fraction, the energy budget equivalent of the ratio of actual to potential evapotranspiration, for use with the Aqua/MODIS sensor. The method normalizes the radiometric surface temperature with normalized difference vegetation index to infer changes in the land surface sensible/latent energy partitioning, and is computed every eight days globally. We tested the algorithm using Terra/MODIS datasets from the year 2000. Potential applications for the evaporation fraction include water resources management, mapping vegetation stress and wildland fire risk.