Saturday, June 12, 2010

New boreal forest biomass maps produced from radar satellite data

Science Daily: Having a large-scale boreal forest biomass inventory would allow scientists to understand better the carbon cycle and to predict more accurately Earth's future climate. However, obtaining these maps has been wrought with difficulty -- until now. A new processing algorithm has been developed using stacks of images from the Advanced Synthetic Aperture Radar (ASAR) on ESA's Envisat satellite that allows for the retrieval of boreal forest biomass well beyond the levels that have been previously reported.

…Boreal forests and woodlands are estimated to cover approximately 14.5% of Earth's land surface, comprising an area of nearly 16 million sq km (about the size of the contiguous 48 states of the US). The boreal forest ecosystem, which spans Russia, northern Europe, Canada and Alaska, comprises interrelated habitats made up of forests, lakes, wetlands, rivers and tundra.

…"Biomass, one of the most essential climate variables defining the functions of the Earth system, is the big unknown factor in the carbon cycle. Since no biomass maps exist with a high level of accuracy, we do not know how much is changing and cannot do calculations with any certainty. With this new algorithm, it is the first time that we have something in hand that may be a first step to a global biomass map," said Prof. Christiane Schmullius with the Friedrich Schiller University Jena.

The BIOMASAR project, sponsored by ESA's Support to Science Element (STSE), has fully validated the algorithm using ASAR data, which is capable of acquiring images regardless of darkness and cloud cover, with existing in-situ information. To validate the algorithm, several test sites were chosen in Scandinavia, Siberia and Canada, where both extensive datasets of ASAR images, acquired in ScanSAR mode at mid-resolution, and in-situ measurements were available…..

Forest growing stock volume (GSV) map of Central Siberia, obtained with the BIOMASAR algorithm using one-year of Envisat Advanced Synthetic Aperture Radar (ASAR) Global Monitoring mode images acquired in 2005. GSV is represented in shades of green between 0--500 cubic metres per hectare. The GlobCover Land Cover map was used as the background for non-forested areas. Map projection: Albers (standard parallels 56 and 73 degree N). (Credit: ESA, Gamma Remote Sensing, Friedrich-Schiller University Jena)

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