The land cover maps were developed at Boston University in Boston, Mass.,
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 last maps of this kind were
produced from data collected in 1992 and 1993 by the National Oceanic and
Atmospheric Administration’s Advanced Very High Resolution Radiometer.
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.
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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
agricultural land.
Color-coded Key
High Resolution Images
1km Western Hemisphere (19.7 MB TIFF)
1km Eastern Hemisphere (25.4 MB TIFF)
4km Global (18.9 MB TIFF)
16km Global (470 KB JPEG)
Animations
Broadcast Quality (70.1 MB Quicktime)
High Quality Web (24.5 MB MPEG)
Moderate Quality Web (6.9 MB MPEG)
Globe Broadcast (128 MB Quicktime)
Globe High Quality (8.6 MB MPEG)
Globe Moderate Quality (2.6 MB MPEG) |
Each MODIS land cover map contains 17 different land cover types, including
eleven natural vegetation types such as deciduous and evergreen forests,
savannas, and wetlands. Agricultural land use and land surfaces with little or
no plant cover—such as bare ground, urban areas and permanent snow and ice—are
also depicted on the maps. Important uses include managing forest resources,
improving estimates of the Earth’s water and energy cycles, and modeling
climate and global carbon exchange among land, life, and the atmosphere.
Carbon cycle modeling is linked to greenhouse gas inventories—estimates of
greenhouse emissions from human sources, and their removal by greenhouse gas
sinks, such as plants that absorb and store carbon dioxide through
photosynthesis. Many nations, including the United States, produce the
inventories annually in an effort to understand and predict climate change.
“This product will have a major impact on our carbon budget
work,” says Professor Steve Running of the University of Montana,
Missoula, who uses the Boston University land cover maps in conjunction with
other weekly observations from MODIS. “With the MODIS land cover product
we can determine current vegetation in detail for each square kilometer; for
example, whether there is mature vegetation, clear cutting, a new fire scar, or
agricultural crops. This means we can produce annual estimates of net change in
vegetation cover. This gets us one step closer to a global picture of carbon
sources and sinks.”
This first map is an important milestone, but the land cover mapping group in
Boston has other projects in progress. “With data collected over several
years,” says Friedl, “we will be able to create maps that highlight
global-scale changes in vegetation and land cover in response to climate change,
such as drought. We’ll also be establishing the timing of seasonal changes
in vegetation, defining when important transitions take place, such as the onset
of the growing season.” |
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This image shows a map of the various land cover types
and their extent across Europe. A belt of deciduous broadleaf and mixed forests
bisects the European continent, stretching from Spain in the southwest, across
parts of France, Germany, Italy, the Balkans, and well into Russia. The large
yellow swaths (croplands) all across the continent indicate agriculture
widespread and robust enough to support Europe’s burgeoning urban centers.
Color-coded Key
High Resolution Images
Africa (5.1 MB TFF)
Asia (6.1 MB TFF)
Australia (4.3 MB TFF)
Europe (7.6 MB TFF)
North America (6.1 MB TFF)
South America (4.8 MB TFF)
Web Resolution Images
Africa (54 KB JPEG)
Asia (74 KB JPEG)
Australia (43 KB JPEG)
Europe (91 KB JPEG)
North America (75 KB JPEG)
South America (48 KB JPEG)
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Launched December 18, 1999, Terra is the flagship of the Earth Observing
System series of satellites and is a central part of NASA’s Earth Science
Enterprise. The mission of the Earth Science Enterprise is to develop a
scientific understanding of the Earth system and its response to natural and
human-induced changes to enable improved prediction capability for climate,
weather, and natural hazards.
For more information and images, see: http://geography.bu.edu/landcover/index.html
Lynn Chandler
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-2806)
Lynn.Chandler.1@gsfc.nasa.gov
Bob Zalisk
Boston University, Boston, Mass.
(Phone: 617/353-7628)
bzalisk@bu.edu |
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This image shows the land cover
types of the United States in different colors. Each land cover type plays a
different role in the carbon cycle. Extensive agricultural lands represent a
massive modification of natural land cover and the carbon budget. Northern
forests have been identified as a long-term sink for carbon, and may be
especially sensitive to climate change.
Color-coded Key
High Resolution Image (14.9 MB TIFF)
West Coast Flyby Animation
Broadcast Quality (472 MB Quicktime)
High Quality Web (12.9 MB MPEG)
Moderate Quality Web (4 MB MPEG) |
