European Space Agency Makes Sharpest Earth Map Ever

PARIS, France, May 6, 2005 (ENS) - The most detailed map ever made of the Earth's land surface is being created with the European Space Agency's Envisat environmental satellite. The GLOBCOVER project aims at producing a global land cover map to a resolution three times sharper than any previous satellite map.

It will be a unique depiction of the face of the planet in 2005, broken down into more than 20 separate land cover classes, the European Space Agency (ESA) said today.

The completed GLOBCOVER map will have numerous uses, including plotting worldwide land use trends, studying natural and managed ecosystems and modelling climate change extent and impacts.

Envisat's Medium Resolution Imaging Spectrometer (MERIS) instrument is being systematically used in Full Resolution Mode for the project, acquiring images with a spatial resolution of 300 metres, with an average 150 minutes of acquisitions occurring daily.

ESA estimates is that up to 20 terabytes of imagery will be needed to mosaic together the final worldwide GLOBCOVER map an amount of data equivalent to the contents of 20 million books.


The most detailed map of Earth ever created takes shape. (Photo courtesy ESA)
The image acquisition strategy is based around regional climate patterns to minimize cloud or snow cover. Multiple acquisitions are planned for some regions to account for seasonal variations in land cover.

Other Envisat sensors will work in synergy with MERIS, the agency explains. The Advanced Synthetic Aperture Radar (ASAR) instrument will be used to differentiate between similar land cover classes, such as wetlands and humid tropical rainforests.

Information from the satellite's Advanced Along Track Scanning Radiometer will be used to correct for atmospheric distortion and to perform what the ESA calls "cloud masking," or the elimination of cloud pixels.

An international network of partners is working with ESA on the two-year GLOBCOVER project, which is taking place as part of the Earth Observation Data User Element.

Participants include the United Nations Environment Programme (UNEP), the UN Food and Agriculture Organisation, the European Commission's Joint Research Centre,, the International Geosphere-Biosphere Programme, and the Global Observations of Forest Cover and Global Observations of Land Dynamics.

"UNEP anticipates being able to put the GLOBCOVER map to good use within its program of assessment and early warning of emerging environmental issues and threats, particularly those of a trans-boundary nature," said Ron Witt of UNEP.

"Changes in land cover patterns, effects of environmental pollution and loss of biodiversity often do not respect national or other artificial boundaries," Witt said. "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."