Evaporative Stress Index (ESI)
Index name: Evaporative Stress Index (ESI).
Ease of use: Green.
Origins: Developed by a team led by Anderson, in which remotely sensed data were used to compute evapotranspiration over the United States. The team was composed of scientists from the United States Department of Agriculture, the University of Alabama-Huntsville and the University of Nebraska-Lincoln.
Characteristics: Established as a new drought index in which evapotranspiration is compared to potential evapotranspiration using geostationary satellites. Analyses suggest that it performs similarly to short-term precipitation-based indices, but can be produced at a much higher resolution and without the need for precipitation data.
Input parameters: Remotely sensed potential evapotranspiration.
Applications: Especially useful for identifying and monitoring droughts that have multiple impacts.
Strengths: Very high resolution with a spatial coverage of any area.
Weaknesses: Cloud cover can contaminate and affect results. There is not a long period of record for climatological studies.
Resources: Calculations of the index are provided in the literature and on the Hydrology and Remote Sensing Laboratory (HRSL) of the USDA-Agricultural Research Service (ARS) website.
Reference: Anderson, M.C., C. Hain, B. Wardlow, A. Pimstein, J.R. Mecikalski and W.P. Kustas, 2011: Evaluation of drought indices based on thermal remote sensing of evapotranspiration over the continental United States. Journal of Climate, 24(8): 2025–2044. DOI: 10.1175/2010JCLI3812.1.