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MODIS Measures Total U.S. Leaf Area
This page contains archived content and is no longer being updated. At the time of publication, it represented the best available science. However, more recent observations and studies may have rendered some content obsolete.
This composite image over the continental United States was
produced with data acquired by the Moderate-resolution Imaging
Spectroradiometer (MODIS) during the period March 24 - April 8, 2000.
The image is a map of the density of the plant canopy
covering the ground. It is the first in a series of images over the continental U.S. produced by the MODIS Land Discipline Group (refer to this site June 2 & 5 for the next two images in the series).
The image is a MODIS data product called "Leaf Area Index," which
is produced by radiometrically measuring the visible and near
infrared energy reflected by vegetation. The Leaf Area Index
provides information on the structure of plant canopy, showing how
much surface area is covered by green foliage relative to total land
surface area. In this image, dark green pixels indicate areas where
more than 80 percent of the land surface is covered by green vegetation, light
green pixels show where leaves cover about 10 to 50 percent of the
land surface, and brown pixels show virtually no leaf coverage.
The more leaf area a plant has, the more sunlight it can absorb for
photosynthesis. Leaf Area Index is one of a new suite of measurements that scientists use to understand how the Earth's land surfaces are changing over time. Their goal is to use these measurements to refine computer models well enough to simulate how the land biosphere influences the natural cycles of
water, carbon, and energy throughout the Earth system.
This image is the first of its kind from the MODIS instrument,
which launched in December 1999 aboard the Terra spacecraft. MODIS
began acquiring scientific data on February 24, 2000, when it first
opened its aperture door. The MODIS instrument and Terra spacecraft
are both managed by NASA's Goddard Space Flight Center, Greenbelt, MD.
Image courtesy Steven Running, MODIS Land Group Member, University of Montana