The global carbon cycle plays a vital role in climate change and is of intense importance to policy makers, but significant knowledge gaps remain in our understanding of it. Several scientists at the Envisat Symposium this week have highlighted research projects using ESA satellites to understand better this complex process.
The total number of carbon atoms on Earth is fixed they are exchanged between the ocean, atmosphere, land and biosphere. The fact that human activities are pumping extra carbon dioxide into the atmosphere, by fossil fuel burning and deforestation, is well known. Because of this, atmospheric carbon dioxide concentrations are higher today than they have been over the last half-million years or so. Scientists are now using satellite instruments to locate sinks and sources of CO2 in the ocean and land. Across land and sea, our world's plant life uses the process called photosynthesis to convert incoming sunlight into chemical energy. Plants accumulate carbon dioxide during photosynthesis and store it in their tissues, making them carbon sinks.
Dr Nadine Gobron of the European Commission's Joint Research Centre (EC-JRC) in Ispra, Italy, is combining daily multispectral observations from Envisat's Medium Resolution Imaging Spectrometer (MERIS) instrument with a sophisticated processing algorithm to reveal global photosynthesis activity on land.
The fraction of incoming solar radiation useful for photosynthesis that is actually absorbed by vegetation a value known as the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) is recognised as an essential climate variable by international organisations including the Global Climate Observing System (GCOS). FAPAR is regularly used in diagnostic and predictive models to compute the primary productivity of the vegetation canopies.
The operational FAPAR MERIS product is derived with the JRC-FAPAR algorithm, which has been designed to exploit the
Contact: Mariangela D'Acunto
European Space Agency