BY MARK HENDERSON, SCIENCE CORRESPONDENT, TIMES ONLINE
SCIENTISTS are assembling the most detailed map of the Earth’s surface yet, using images from a European satellite.
The Globcover project will produce a global portrait of the world’s land cover with a resolution three times sharper than any previous satellite map, enabling researchers to study the impact of global warming and environmental change with unprecedented accuracy.
The map is being pieced together using millions of images taken by Envisat, an environmental monitoring satellite launched by the European Space Agency in 2002.
It will have a resolution of 300 square metres per pixel, a great improvement on the previous best for land cover of a kilometre per pixel produced by older satellites in 2000. The final “mosaic” formed by the images will contain 20 terabytes of data — or enough information to fill 20 million books.
The project will assign one of 20 land cover types — such as wetland, rainforest, tundra or desert — to each 300-metre square, producing a map of the extent of the world’s ecosystems that can be used to monitor environmental change.
The United Nations Environment Programme (UNEP), one of the six international partners in Globcover, plans to use the information to analyse how climate change, urbanisation and other trends are altering the planet’s land cover. Ron Witt, of UNEP, said: “Changes in land-cover patterns, effects of environmental pollution and loss of biodiversity often do not respect national or other artificial boundaries. An updated view of such problems — or their effects — from interpreted space imagery should offer a large boost to UNEP’s effort to monitor the health of the planet and our changing environment.”
Envisat is spending on average of 2½ hours every day capturing images for the map. It will make multiple passes over many parts of the world to secure accurate pictures of land that is obscured by cloud or snow cover. A map of Europe has been produced, from 160 separate Envisat images.
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