Vegetation Images Show Drought in Western US (WMS)

Satellite data can gauge the health of plants, which is a good indicator of drought. The Normalized Difference Vegetation Index (NDVI) measures how dense and green plant leaves are. NDVI images are useful as a measure of drought when compared to "normal" plant health. Scientists calculate average NDVI values for an area to find out what is normal at a particular time of year. This animation uses satellite imagery to show changes in vegetation between 1999 and 2003. 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 is a wide view showing the western United States. The data were measured by the vegetation instrument on Europes SPOT-4 satellite, and were provided by DigitalGlobe-SPOT under agreement with the U.S. Department of Agriculture Foreign Agricultural Service (USDA-FAS). Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional