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GCOS Essential Climate Variables (ECV) Fire Disturbance (Burnt Area): Changes in land cover are important aspects of global environmental change, with implications for ecosystems, biogeochemical fluxes and global climate. Land cover change affects climate through a range of factors from albedo to emissions of greenhouse gases from the burning of biomass. Deforestation inter alia increases the amount of carbon dioxide (CO2) and other trace gases in the atmosphere. When a forest is cut and burned to establish cropland and pastures, the stored carbon joins with oxygen and is released into the atmosphere as CO2. The IPCC notes that about three-quarters of the anthropogenic emissions of CO2 to the atmosphere during the past 20 years were due to fossil fuel burning. The rest was predominantly due to land use change, especially deforestation. In 2005, a number of developing countries proposed to incorporate deforestation prevention into the Kyoto Protocol, in part through an emissions trading system. The initiative, known as REDD, (Reducing Emissions from Deforestation in Developing countries) would allow developing countries to sell emissions savings from forest conservation. Developed countries would buy the savings to credit against their own emissions targets. IGOS has set up an Integrated Global Carbon Observation (IGCO) Theme (report available from www.igospartners.org ) to develop a flexible, robust strategy for international global carbon observations over the next decade. A key component of IGCO is terrestrial carbon observations aimed at the determination of terrestrial carbon sources and sinks with increasing accuracy and spatial resolution. The IPCC has highlighted an improved understanding of carbon dynamics as vital in tackling one of the biggest environmental problems facing humanity. The IGCO work will be an essential input to the implementation of the United Nations Framework Convention on Climate Change (UNFCCC), particularly on the role of natural sinks in meeting targets under the UNFCCC Kyoto Protocol. Satellite observations allow scientists to map land cover and the dynamics of fire disturbance, and track two key elements of Earth’s vegetation – the ‘Leaf Area Index’ (LAI) and the ‘Fraction of absorbed Photo-synthetically Active Radiation’ (fAPAR). LAI is defined as the one-sided green leaf area per unit ground area in broadleaf canopies, or as the projected needle leaf area per ground unit in needle canopies. fAPAR is the fraction of photosynthetically active radiation absorbed by vegetation canopies. Both LAI and fAPAR are data necessary for understanding how Sunlight interacts with the Earth’s vegetated surfaces. Satellite Observations: Multiple types of satellite observations are used in agricultural applications. Space imagery provides information which can be used to monitor quotas and to examine and assess crop characteristics and planting practice. Information on crop condition, for example, may also be used for irrigation management. In addition, data may be used to generate yield forecasts, which in turn may be used to optimise the planning of storage, transport and processing facilities. Classification and seasonal monitoring of vegetation types on a global basis allow the modelling of primary production – the growth of vegetation that is the base of the food chain – which is of great value in monitoring global food security. A number of radiometers provide measurements of vegetation cover, including the ATSR series, AVHRR/3, MODIS, MERIS, SEVIRI and Vegetation. These instruments are helping production of global maps of surface vegetation for modelling of the exchange of trace gases, water and energy between vegetation and the atmosphere. Multi-directional and polarimetric instruments (such as MISR and POLDER) will provide more insights into corrections of land surface images for atmospheric scattering and absorption, as well as Sun-sensor geometry, allowing better calculation of vegetation properties. Synthetic aperture radars (SARs) are used extensively to monitor deforestation and surface hydrological states and processes. The ability of SARs to penetrate cloud cover and dense plant canopies makes them particularly valuable in rainforest and high-latitude boreal forest studies. Instruments such as ASAR, SAR (RADARSAT), and PALSAR provide data for such applications as agriculture, forestry, land cover classification, hydrology and cartography. CEOS and GCOS have concluded that many of the Essential Climate Variables related to vegetation and supported from space will require reprocessing of the moderate resolution historical record (in particular AVHRR) to be of greater value for climate purposes, and appropriate actions have been defined, including the development of enhanced calibration and validation schemes which guarantee long-term stability and consistency over different temporal and spatial scales. Research topics like scaling, and the development of ‘community radiative transfer models’ integrated into sophisticated assimilation schemes, are of paramount importance for an integrated approach. (Satellite Missions) (from the CEOS web site) Fire Dicturbance (Active Fires): Land surface temperature varies widely with solar radiation. It is of help in interpreting vegetation and its water stress when the range of temperatures between day and night and from clear sky to cloud cover are compared. Estimates of greenhouse gas emissions due to fire are essential for realistic modelling of climate and its critical component, the global carbon cycle. Fires caused deliberately for land clearance (agriculture and ranching) or accidentally (lightning strikes, human error) are a major factor in land cover changes, affecting fluxes of energy and water to the atmosphere. On a local scale, surface temperature imagery may be used to refine techniques for predicting ground frost and to determine the warming effect of urban areas (urban heat islands) on night-time temperatures. In agriculture, temperature information may be used, together with models, to optimise planting times and provide timely warnings of frost.Measurements of surface temperature patterns may also be used in studies of volcanic and geothermal areas and resource exploration.Satellite Observations: Land surface temperature measurements are made using the thermal infrared channel of medium/high resolution multi-spectral imagers in low Earth orbit. In addition, visible/infrared imagers on geostationary satellites also provide useful information, with the advantage of very high temporal resolution. However, difficulties remain in converting the apparent temperatures as measured by these instruments into actual surface temperatures – variations due to atmospheric effects and vegetation cover, for example, require compensation using additional imagery/information. A number of capable sensors designed to provide land surface temperature data are currently operating or planned. These include advanced sounders (IASI, HIRS/4) on operational meteorological platforms. On the NPOESS missions, VIIRS will combine the radiometric accuracy of AVHRR with the high spatial resolution of the DMSP’s OLS instrument, and the CMIS imager/sounder will measure thermal microwave emissions from land surfaces. The Hot Spot Recognition Sensor (HSRS) on BIRD (launched 2001) has already demonstrated its value as a purpose-built fire detection instrument while MODIS provides regular sampling of active fires, SEVIRI observes the diurnal cycle of fire occurrence in Africa and the ATSR series, despite not being designed for active fire observations, has produced the longest record of hot spot detection (at night). ESA offers a monthly world fire atlas product available online at dup.esrin.esa.it/ionia/wfa. (Satellite Missions) (from the CEOS web site) Data, Product, Metadata and Information Access
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