Vegetation plays a critical role on Earth as all animals and humans ultimately depend on it for food. Plants often provide a local habitat for other species to live in, and constitute a major source of raw materials for human activities. Wood in particular constitutes a critical source of energy storage for a large fraction of humanity which relies on it for heating and cooking. It is especially significant as a 'sink' of carbon that might otherwise enter the atmosphere as carbon dioxide and hasten global warming.
Envisat's Medium Resolution Imaging Spectrometer (MERIS) acquires multispectral imagery of the Earth, and is used to monitor the state and evolution of the planetary vegetation cover. In particular the instrument's standard Level-2 product on land, known as the MERIS Global Vegetation Index (MGVI) provides FAPAR values based on reflected radiation from the Earth's land surface. EC-JRC is responsible for the processing algorithm that yields the MGVI product.
"It is a complex task to extract the required information from the reflected light MERIS measures," explains Nadine Gobron of EC-JRC. "It requires the development of mathematical tools to minimise the effects due to scattering from atmospheric particles, the presence of soils and the changing geometry of illumination and observation."
The validation of MGVI is in fact an ongoing activity, along with that for a family of related FAPAR algorithms developed by JRC for other satellite sensors, including NASA's MODIS and SeaWiFS, intended to ensure the availability of a long time series of global products. The latter are essential to assess environmental trends, guide policy making and support sustainable development.
"Considerable efforts are made to eval
Source:European Space Agency