Earth is Becoming a Greener Greenhouse
The Data: Dr. Tucker of NASA Goddard Space Flight Center developed the Normalized Difference Vegetation Index (NDVI) product to help determine
the "greening" of plant life. This index uses red and near-infrared solar radiation reflected back to sensors aboard NOAA's polar-orbiting satellites.
The sensors observed every patch of land on the Earth, at least once a day, continuously from July of 1981. Processing of such massive amounts of data
is a tedious task even on modern day computers and requires special methods to correct for atmospheric blurring of the earth surface. The vegetation
index shows greening and browning of plants as they relate to seasonal changes and conditions such as drought or abundant rainfall. A color image of
yearly average greenness is shown below. Notice the reddish-purple tones in the tropics - these are the tropical forests. The greenish tones in
northern Eurasia and North America depict greenness of the needle trees.
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