The GBFM radar mosaic of the Eurasian Taiga: selected topics on geo-location and preliminary thematic products

In the context of the Global Boreal Forest Mapping project (GBFM), an initiative of the Japan Aerospace Exploration Agency (JAXA), a continental scale radar mosaic of the Eurasian Taiga was compiled. The mosaic is composed of some 520 strip-images (typically covering 80 km by 2500 km each) acquired in 1997-98 by the L-band SAR aboard the JERS-1 spacecraft. The mosaic was assembled in two phases. Coverage in the first stage included the area between the Ural Mountains in the west, Bering Strait in the east, Arctic Ocean in the north and the Korean Peninsula in the south. In the second phase an extended version was produced that comprises the European part of the Boreal ecosystems west of the Ural Mountain and up to the European Union region. Pixel spacing of the high resolution final products is 100 m and map projection is Albers equal-area conical. In this paper selected topics are presented related to a revision of the mosaic geometry. This step was called for to improve the internal consistency and assure proper absolute geo-location of the mosaics with respect to reference data sets. It consists of: i) a data representation (virtual frames) for handling the strip-images in smaller units that are more effective for dealing with local distortions; and ii) inclusion of control points derived from the Landsat GeoCover data sets. Results characterizing the mosaic geometric accuracy in terms of root mean square residuals are reported. Finally, we present, as a first thematic result, a vegetation map at coarse resolution (900 m) derived by a combination of the Global Land Cover 2000 map and the GBFM radar mosaic