Satellite data can gauge the health of plants, which is a good indicator of drought. Satellite imagery shows changes in vegetation between 1999 and 2003. The Normalized Difference Vegetation Index (NDVI) measures how dense and green plant leaves are, which suggests overall vegetative health. The NDVI images are also useful as a measure of drought when compared to 'normal' plant health. NASA scientists calculate average NDVI values for an area to find out what is normal at a particular time of year. This data was measured by the vegetation instrument on Europe's SPOT satellite provided by DigitalGlobe/SPOT, under agreement with the U.S. Department of Agriculture Foreign Agricultural Service (USDA/FAS).
In 2002, drought had settled across the Midwest. Large dark brown sections of eastern Colorado show where vegetation was less lush and healthy than normal.
This version of the visualization focuses on the southwestern United States.
Please give credit for this item to: NASA/Goddard Space Flight Center
Scientific Visualization Studio. DigitalGlobe/SPOT data provided under agreement with the U.S. Department of Agriculture Foreign Agricultural Service (USDA/FAS)
The Blue Marble Next Generation data is courtesy of Reto Stockli (NASA/GSFC) and NASA's Earth Observatory.
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GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 188.8.131.52.0