Online Drought Indicators and Indices

Normalized Difference Vegetation Index (NDVI)


Index name: Normalized Difference Vegetation Index (NDVI).

Ease of use: Green.

Origins: Developed from work done by Tarpley et al. and Kogan with the National Oceanic and Atmospheric Administration (NOAA) in the United States.

Characteristics: Uses the global vegetation index data, which are produced by mapping 4 km daily radiance. Radiance values measured in both the visible and near-infrared channels are used to calculate NDVI. It measures greenness and vigour of vegetation over a seven-day period as a way of reducing cloud contamination and can identify drought-related stress to vegetation.

Input parameters: NOAA AVHRR satellite data.

Applications: Used for identifying and monitoring droughts affecting agriculture.

Strengths: Innovative in the use of satellite data to monitor the health of vegetation in relation to drought episodes. Very high resolution and great spatial coverage.

Weaknesses: Data processing is vital to NDVI, and a robust system is needed for this step. Satellite data do not have a long history.

Resources: The literature describes the methodology and calculations. NDVI products are available online,


Kogan, F.N., 1995: Droughts of the late 1980s in the United States as derived from NOAA polar-orbiting satellite data. Bulletin of the American Meteorology Society, 76(5):655–668.

Tarpley, J.D., S.R. Schneider and R.L. Money, 1984: Global vegetation indices from the NOAA-7 meteorological satellite. Journal of Climate and Applied Meteorology, 23:491–494.

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