Spanish Forest Fire Aftermath Surveyed By Envisat

As the Spanish authoritiesassess the fire's aftermath, a rapid damage estimate has been performedusing Envisat's Medium Resolution Imaging Spectrometer (MERIS)instrument.

A 24 July MERIS Full Resolution mode image with aspatial resolution of 300 metres was processed to reveal burned areasby a team led by Dr. Federico González-Alonso, head of the Madrid-basedLaboratorio de Teledetección (Remote-sensing Laboratory) of theInstituto Nacional de Investigación y Tecnología Agraria y Alimentaria(National Institute for Agriculture, Food Research and Technology orINIA).

"MERIS measures the solar radiation reflected by the Earthin 15 selectable spectral bands in the visible and near infra-red,"explained González-Alonso. "We utilised bands that were particularlysensitive to vegetation, then performed an automatic matched filteringanalysis on the stacked bands to designate 'endmembers' - spectrallypure areas that could be visually classified as very burnt.

"Thefile obtained was reclassified by modifying the histogram or graphicalbar used, so pixels with values over 0.3 were considered burnt. Theresulting perimeter gives us a burnt area estimate of 11 313 hectares."This figure compares well to forest fire burnt area estimates fromother sources of 12 000 hectares.

"The results of our completedstudy will be sent to the Spanish Ministry of Environment for economic,social and ecological damage assessment," González-Alonso added. "Ourteam has been studying the use of MERIS data for fire-damage assessment- the obtaining of images from ESA in near-real time via the internetbeing an essential point in this kind of application."

"Theresults achieved so far show that estimates can be extremely useful notonly in establishing the scale of the damage but also for thesubsequent forest renewal projects and for subsidy management."

Theteam is also participating in ESA's Dragon Programme of cooperationwith Chinese researchers, using MERIS Full Resolution imagery to mapforest fires across China.

González-Alonso explained that MERIS'svisible and infra-red multispectral imaging capability combined with abetter spatial resolution than comparable satellite sensors make itespecially useful for providing fire-damage information.

MERIS'scapability is being employed in a variety of different projects,including as part of GLOBCARBON, a project to better characterisechanges in the amount of land-based carbon on a global basis across tenyears from 1997.

Monitoring the location, duration and affectedarea of forest fires is an important part of GLOBCARBON, since blazesare a major way for carbon to be released from land-based 'sinks' intothe atmosphere. The project, part of ESA's Data User Element, shouldimprove scientific understanding of the carbon cycle and improveclimate change modelling.

MERIS is also being utilised incombination with other satellite sensors for the Risk-EOS initiative,which is rolling out a series of operational services for fire andflood risk management, with burn scar mapping initially being offeredwithin a total area of 180 000 square kilometres across two parts ofEurope: Spain's Castilla y Leon Region and the Éntente area of southernFrance.

Risk-EOS is taking place as part of the GMES ServicesElement (GSE), a suite of Earth Observation services being developed aspart of the Global Monitoring for Environment and Security (GMES) jointendeavour between ESA and the European Commission, aimed at mergingground- and space-based information sources to develop a comprehensiveplanetary monitoring capability in support of Europe's environment andsecurity goals.

A follow-on to MERIS is planned as payload forthe GMES-1 spacecraft, intended to support operational GMES servicesinto the next decade.