The waveform of SLA-02 is a measure of the height distribution of the vertical structure in the 100-m diameter footprint. The round-trip travel time duration of waveform digitizer bin for the SLA-02 orbits (1 and 3) used in this study is 4 ns, corresponding to a vertical distance of about 0.6 m. The height and horizontal position accuracies of the SLA-02 data used in this study are on the order of 1 m, and about 100 m, respectively (Carabajal et al., 1999; Luthcke et al., 2002). In order to verify (or have a high confidence on) SLA-02 data, footprints of some SLA-02 laser shots were visited in summer of 2002 as part of GSFC and Sukachev Forest Institute field work for a Siberia Land Cover Mapping project. SLA-02 footprints were marked on Landsat-7 ETM images, and then selected for field observations based on cover type, accessibility, and location of the footprint being well inside a homogeneous area of the cover type.