The sharpest ever satellite map of Earth
May 18, 2007 The European Space Agency's GlobCover project has unveiled the most detailed portraits ever of the Earth's land surface. Using around 40 Terabytes of images captured from the ESA's Envisat, the maps, ten times sharper than anything produced previously, the GlobCover maps will have numerous uses, including plotting worldwide land use trends, studying natural and managed ecosystems and modelling climate change extent and impacts.
A composite Earth map taken at 300 metre resolution between May and June 2005 can be viewed here (1mb jpg).
The United Nations Environment Programme’s (UNEP) Ron Witt said: "The GlobCover data sets should allow UNEP to do frequent monitoring of environmentally-critical sites and known 'hot spots' in areas we have under examination around the globe, and to update our knowledge of such changing environmental conditions, in order to alert the global community to emerging problems before it is too late for decision-makers and civil society to take action in this regard."
Jean-Louis Weber highlighted the importance of the GlobCover products in the framework of the European Environmental Agency (EEA): "From the point of view of time scales, the contribution expected from GlobCover is of paramount importance. Combined with the Corine data on which the current accounts of land cover change at the European scale are based, a regularly updated GlobCover is expected to play a key role in the implementation of nowcasting procedures, necessary for delivering up-to-date data on land cover change at the European scale at a pace compatible with the main socio-economic indicators."
The Food and Agriculture Organization of the United Nations (FAO) will use GlobCover products to support many of its activities. "GlobCover products should constitute an important interpretation asset in support of more dynamic environmental parametres such as rainfall and vegetation condition for FAO's global and national food security early warning programmes on which ESA and FAO cooperate closely," FAO’s Dr. John Latham explained.
"It will also significantly contribute to the monitoring and assessment of global land cover and as such will support the contribution of FAO to the assessment of land degradation and the monitoring of global forest cover."
The products are based on Envisat's Medium Resolution Imaging Spectrometer (MERIS) instrument working in Full Resolution Mode to acquire images in polar orbit at an altitude of 800 km with a spatial resolution of 300 metres.
The global composites are produced by processing MERIS images together in a standardised way. Thirteen out of 15 MERIS spectral bands are processed with an upgraded algorithm including tools for ortho-rectification, cloud screening and full atmospheric correction, which accounts also for aerosol.
The global land cover map, which is ten times sharper than any previous global satellite map, is derived by an automatic and regionally adjusted classification of the MERIS global composites. The 22 land cover classes are defined according to the UN Land Cover Classification System (LCCS).
GlobCover is taking place as part of ESA’s Earth Observation Data User Element (DUE). An international network of partners is working with ESA on the project, including the United Nations Environment Programme (UNEP), the Food and Agriculture Organisation (FAO), the European Commission's Joint Research Centre (JRC), the European Environmental Agency (EEA), the International Geosphere-Biosphere Programme (IGBP) and the Global Observations of Forest Cover and Global Observations of Land Dynamics (GOFC-GOLD) Implementation Team Project Office.
"GlobCover is an excellent example of a successful inter-agency partnership, and we are especially pleased that the LCCS – a joint FAO/UNEP standard – is being used as the basis of the classification," Latham said.
The GlobCover processing chain has been developed by MEDIAS France, which is also operating the processing chain, together with Brockmann Consult, the Université catholique de Louvain and partners.