Pre-Launch Development of Sentinel-3 SLSTR Active Fire Product

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The Sea and Land Surface Temperature Radiometer (SLSTR) is a new ESA instrument flying on the Sentinel-3 satellites from 2013 to 2025. Sentinel-3 is an Ocean and Medium-Resolution Land Mission primarily dedicated to delivering data to drive Global Monitoring for Environment and Security (GMES) Operational Services, as well as providing invariable data for science applications. SLSTR builds on the heritage (A)ATSR series of instruments, having unique capabilities for long-term, high radiometric performance observation of Earth's oceans, land surface and atmosphere. However, SLSTR has been designed from the start specifically to make high quality observations of the ocean, atmosphere and land, including in relation to actively burning fires. Active Fire information is one of the Essential Climate Variables (ECVs) designated by the Global Climate Observing System (GCOS) as required for supporting consistent global monitoring of land change dynamics and their impacts on climate, in order that climate change estimates for the UNFCCC maybe properly updated. The importance is illustrated by the fact that vegetation fires are believed to emit an annual amount of carbon to the atmosphere that is estimated as perhaps 40% of that due to fossil fuel burning. The Implementation Plan of GCOS is the most advanced Earth Observation framework for implementing a UN convention. The plan emphasizes the need for operational observations for thirteen Essential Climate Variables (ECV) in the terrestrial domain; among them Fire Disturbance. In view of this, a number of the specifications of the SLSTR instrument have been especially adapted for providing the necessary radiometric observations for delivering useful information over active fire locations, most importantly the inclusion of two new radiometric 'fire' channels centered on 3.7 microns and 10.8 microns that have low-gain, wide dynamic range settings that prevent saturation over even the most intensely burning fires. SLSTR therefore has the capability to deliver the first operational active fire product available at the global scale. The proposal aims to maximize the scientific benefit and the return on UK and ESA investment in SLSTR by developing, evaluating and and testing the series of algorithms necessary to deliver an optimized, high quality Active Fire product from this instrument, including fire location, time and fire radiative power (FRP) output with quantified uncertainties. From this information rates of vegetation fuel consumption, carbon, trace gas and aerosol release can be calculated, along with other subsequently derived parameters. It is expected that an operational product resulting from application of these algorithms would find use in both operational GMES Services, such as the Atmospheric Service envisaged as developing from the current ECMWF-led GEMS project, and by National Agencies such as the UK Met Office, and in a wide variety of science applications including those related to carbon cycle science and studies of atmospheric constituents. Current use by operational agencies of geostationary Active Fire and FRP products developed by the PI over Europe and Africa have demonstrated the value of such data for near-real time plume forecasting in relation to air quality warnings for example. Without the time and support necessary to develop and test a suite of algorithms specifically for SLSTR, any fire product derived from the radiances measured by the instrument will be limited to ports of existing algorithms developed for other sensors and so will fail to make use of the unique capabilities of the SLSTR [such as its dual view capability and fire-adapted spectral channels] and its position on the Sentinel-3 satellite carrying a suite of complementary instruments. This NCEO Mission Support project will ensure our ability to deliver optimum active fire information from SLSTR for use in both science applications and operational services.