Nasa News Stories Archive

RELEASE NO: 02-126

August 13, 2002

NASA’s Terra Satellite Refines Map of Global Land Cover

   

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 monitoring objectives.

   

 
Global Land Cover
 

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.
 

 

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.”

 

Europe Land Cover Classification
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)

 
US Land
Cover
 

This image shows the land cover types of the United States in different colors. Each land cover type plays a different role in carbon, climate, and water cycles. Land cover maps help scientists understand how human and natural activities affect the Earth system.

Midwest
Grasslands that once covered much of the central United States have been converted to agricultural land. Expanding human populations will increase pressure on grassland ecosystems, and land cover mapping will be necessary to monitor both the extent and quality of farmland as well as to protect important plant and animal habitat.

Northeast
Urban growth is a key land cover issue for the Northeast. Baltimore and Washington appear to be growing into a single urban corridor, replacing the few remaining patches of forest and mixed vegetation landscapes. Recent evidence that urbanization alters climate and rainfall patterns means mapping the urban areas will be important for land use planning and regional weather forecasting.

Northwest
The expansive forests of the Pacific Northwest are an important ecological and commercial asset. Land cover mapping helps assess forest extent and quality. While urban sprawl may be the concern near Seattle, on the eastern slopes of the mountains, water availability for dry-land farming across the Columbia River Plateau is key.

Rocky Mountains
Evergreen forests cover the slopes of the Rockies, while lowlands receive less moisture and support grasslands to the east and open shrublands to the west. Land use planners are battling urban sprawl along the Front Range in Colorado. Although dominated by Denver, other areas north and south hint at a rapidly expanding urban corridor. Land-cover mapping at the wildland-urban interface is important for resource management in fire-prone areas.

Southeast
Farmlands and forests dominate the Southeast. Mapping land cover along coastal regions will become increasingly more important if sea levels continue to rise. In southern Florida, a blue patch of land marks one of the U.S.' largest remaining wetlands-the Florida Everglades. Its proximity to the Miami urban corridor to the east means land cover and land use must be carefully observed to maintain ecosystem quality.

Southwest
Open shrubland dominates the semi-arid Southwest, with considerable amounts of barren or sparsely vegetated land as well. Different land cover types have varied influences on the regional water cycle. In an area where moisture is in short supply, large urban areas such as Los Angeles and agricultural areas must carefully plan water use. Accurate mapping of land cover is critical to regional climate models that forecast water resources, as well as for resource management in fire-prone areas, particularly at the wildland-urban interface.

South-central US
The Mississippi River Valley looks vastly different than it would have three hundred years ago. Millions of acres of wetlands have been lost as humans have altered the river and its flood plain to create agricultural land along the river, contributing to catastrophic floods. Mapping land cover along river systems helps scientists predict where floods are likely to occur and to plan land cover change carefully.

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.

Images by Boston University and NASA Goddard Space Flight Center

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

 

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)

Back to: News