It will be a unique depiction of the face of our planet in 2005, broken down into more than 20 separate land cover classes. 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.
The estimate 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 image acquisition strategy is based around regional climate patterns to minimise 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 Advanced Synthetic Aperture Radar (ASAR) instrument will be used to differentiate between similar land cover classes, such as wetlands and humid tropical rainforests. And information from the satellite's Advanced Along Track Scanning Radiometer will be used to correct for atmospheric distortion and to perform '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 (DUE).
Participants include the United Nations Environment Programme (UNEP), the Food and Agriculture Organisation (FAO), the European Commission'
Contact: Mariangela D'Acunto
European Space Agency