NASA | The Evaporative Stress Index

The Evaporative Stress Index (ESI) provides objective, high-resolution information about the evaporation of water from land surface. The ESI model combines satellite data with other meteorological factors to determine how much water is used by crops and vegetation.

The resulting data helps to detect drought. This visualization shows ESI data for 2010, 2011, and 2012. 2010 was a relatively wet year despite occasional drought. In 2011, the ESI shows extremely dry conditions across all of Texas, Louisiana, and Oklahoma, tracking one of the country’s most devastating droughts.

In 2012, the ESI shows plant stress in the Corn Belt region as early as May. These warning signs later developed into a full drought that impacted the world’s corn and soy been supply. The kind of early-warning detection system ESI provides will enhance the US arsenal of drought monitoring tools and help farmers adapt to drought before it evolves.