deforestation
Changes in NDVI values in Amazonia:
October 2000 through May 2001. Notice the NDVI oscillations around Lake Titicaca in the lower left corner, on the border between Peru and Bolivia

MODIS Vegetation Index for Amazonia

NDVI, short for Normalized Difference Vegetation Index, is a rough measurement of the amount of vegetation present on the surface of the earth. NDVI is calculated by ratioing satellite observations in the Near Infra-Red and Visible spectrums. Many current Earth science models utilize NDVI as their core land surface data set.

Generally speaking the lower the NDVI value, the less vegetation there is on the surface. Values below 0.1 are indicative of bare soil or snow while higher values, 0.6 to 0.8 and above, indicate forests. In the animation above, the deep purple and blue colors are tropical rainforest while the browns indicate dry soil.

The recent launch of the MODIS instrument aboard NASA's Terra satellite has allowed for increased accuracy in NDVI measurements. The University of Maryland currently produces 16-day NDVI composites for the conterminous United States and for selected areas around the world. The data set above was designed for use by the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA).

Visit GLCF product pages for more information on the UMD MODIS VI product. To download the UMD MODIS VI product use the Earth Science Data Inteface

Global Land Cover Change
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