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News  ESA leads the way to map boreal forest
How best to map ‘boreal’ or northern forest with spaceborne radar is the focus of an ESA campaign currently underway in northern Sweden. By answering this question, the campaign addresses one of the key objectives of the candidate Earth Explorer BIOMASS mission. BIOMASS is one of six candidate Earth Explorer missions that has just completed assessment study and will be presented to the science community at a User Consultation Meeting in January 2009. Up to three of the missions will subsequently be selected for the next stage of development (feasibility study), leading to the eventual implementation of ESA’s seventh Earth Explorer mission.
Since forest biomass is half carbon, the BIOMASS mission, if selected, is expected to greatly improve our knowledge of how much carbon is being stored, where it is being stored and better quantify carbon fluxes between land and the atmosphere – important for understanding more about the global carbon cycle and climate change.
P-band. This wavelength is uniquely sensitive to mapping biomass from space. Malcolm Davidson, Head of ESA’s Campaign Unit explains, "The BioSAR 2008 campaign represents the first-ever ESA airborne Synthetic Aperture Radar (SAR) campaign over northern boreal forest. Because of the importance of boreal forests for the BIOMASS mission, and the global carbon cycle in general, highly accurate and robust methods for transforming the P-band radar signals into forest biomass maps are required. By collecting airborne SAR measurements at P-Band over boreal forest and comparing these to extensive measurements made on the ground we can ensure that the satellite mission will accurately map forest biomass across this unique biome."
E-SAR (Experimental Synthetic Aperture Radar) instrument. Ground measurements are also taken of essential forest characteristics such as biomass, forest height and ground conditions by the Swedish University of Agricultural Sciences in Umeå (SLU) supported by the Swedish Defence Research Agency (FOI) and Sweden’s Chalmers University. In addition, forest height measurements of the entire test site were made this summer using a sophisticated helicopter-based laser scanning system.
"We are very pleased that the Krycklan test site was selected for the campaign," says Johan Fransson from SLU. "It provides us with an excellent opportunity to conduct a large-scale inventory of forest properties in our research site and complements parallel efforts being made in our department to develop new methods for assessing and mapping forest resources using remote sensing. We expect to learn a lot from this campaign."
Beyond the immediate needs of the BIOMASS mission, the interest in the campaigns is expected to be enormous, as a complete remote sensing dataset and simultaneously acquired ground data are rare. Once the activity has been completed, the dataset will be made available to the wider scientific community through ESA.
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