Evi

EVI, or Enhanced Vegetation Index, is a remotely sensed index designed to quantify vegetation greenness while minimizing atmospheric and soil background influences. It is widely used to monitor vegetation health, phenology, and productivity across regional and global scales. The index was introduced by Huete et al. in 1997 to improve upon the NDVI in dense canopies, by incorporating an optimized blue-band adjustment and a canopy-correction term. The standard MODIS formulation is EVI = G × (NIR − Red) / (NIR + C1 × Red − C2 × Blue + L), with G = 2.5, C1 = 6, C2 = 7.5, and L = 1.0. It uses near-infrared, red, and blue bands, and has since been adapted for other sensors such as Landsat and Sentinel.

Applications include monitoring vegetation dynamics, drought response, crop yield estimation, and land-cover change. Compared with NDVI, EVI tends to be more sensitive in areas of high biomass and is less affected by soil brightness and atmospheric scattering, though it still requires good atmospheric correction and cloud-free data.

Limitations include dependence on optical data, sensitivity to sensor calibration and viewing geometry, and reduced interpretability in non-vegetated areas. Data sources include MODIS, Landsat, and Sentinel series, enabling long-term time series and climate-vegetation research.

Notes: the acronym EVI is used in other fields (for example Enhanced Vision Instrument in aviation and Environmental Vulnerability Index in disaster risk assessment); this article describes the Enhanced Vegetation Index in remote sensing.

---