By carefully measuring the wavelengths and intensity of visible and
near-infrared light reflected by the land surface back up into space,
the Moderate-resolution Imaging Spectroradiometer (MODIS) Team can
quantify the concentrations of green leaf vegetation around the world.
The above MODIS Enhanced Vegetation Index (EVI) map shows the density of
plant growth over the entire globe. Very low values of EVI (white and
brown areas) correspond to barren areas of rock, sand, or snow. Moderate
values (light greens) represent shrub and grassland, while high values
indicate temperate and tropical rainforests (dark greens). The MODIS EVI
gives scientists a new tool for monitoring major fluctuations in
vegetation and understanding how they affect, and are affected by,
regional climate trends.