New NASA land cover maps are providing scientists with the most refined
global picture ever produced of the distribution of Earth’s ecosystems and
land use patterns. High-quality land cover maps aid scientists and policy makers
involved in natural resource management and a range of research and global
The land cover maps were developed at Boston University in Boston, MA.,
using data from the Moderate Resolution Imaging Spectroradiometer (MODIS)
instrument on NASA’s Terra satellite. The maps are based on a digital
database of Earth images collected between November 2000 and October 2001.
“These maps, with spatial resolution of 1 kilometer (.6 mile), mark a
significant step forward in global land cover mapping by providing a clearer,
more detailed picture than previously available maps,” says Mark Friedl,
one of the project’s investigators.
The MODIS sensor’s vantage point of a given location on Earth changes
with each orbit of the satellite. An important breakthrough for these maps is
the merging of those multiple looks into a single image. In addition, advances
in remote sensing technology allow MODIS to collect higher-quality data than
previous sensors. Improvements in data processing techniques have allowed the
team to automate much of the classification, reducing the time to generate maps
from months or years to about one week.
This image shows global land
cover types in different colors. Each land cover has a different effect on
carbon and climate cycles. Snow and ice cool the planet by reflecting sunlight.
Tropical rainforests are part of an intricate land-atmosphere relationship that
is disturbed by land cover changes such as deforestation. Perhaps the most
significant human alteration of land cover is the creation of large areas of