Drought Conditions in North America

November 14, 2000


Provided by: NOAA, NASA Earth Observatory
Summary authors & editors: Jim Foster

The above image shows areas of drought for North America during August of 2000. The brown shades represents diminished plant growth, and the green shades represent areas where the vegetation growth is greater than average. This is a multi-spectral drought index developed by Dr. Compton Tucker of NASA, which improves upon the data from the Normalized Difference Vegetation Index (NDVI), created 20 years ago to measure the absorption and reflectance of sunlight by plants using satellite observations. Different wavelengths are used to gather information about how much energy the plants are absorbing or reflecting. When vegeation is stressed, it'll limit its chlorophyll production compared to that of healthy vegetation - plants will not grow. The brown areas in the western US show why wildfires were so widespread this summer in the Rocky Mountains. Notice that the Middle Atlantic region is also showing signs of diminished growth; a precursor to the fires that occurred two weeks ago in the mountains of Virginia and North Carolina. Much of the deep south has been experiencing very dry conditions for a good portion of the year.

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