Academy of Sciences of the Czech Republic, Dolejskova 5, Praha 8, 182 00, Czech Republic

Abstract: To assess the terrain effects on the Geoscience Laser Altimeter System (GLAS) waveform and canopy height retrieval, the 3-D lidar waveform model was used to simulate the GLAS waveform for the nine scenes with the slopes increasing from 0 to 30 ° in 1 °. When slope increased from 0 ° to 10 °, the magnitude of the canopy peak decreased by approximately 2/5 to 3/5, but the magnitude of the ground peak decreased by more than 4/5 for all the simulated scenes. The critical slope angle is in direct proportion to canopy height, and slightly decreases with the increased stand density. Further analysis showed that average error for the RH100 was 5.4 m when the slope was 10 °, and reached 9.4 m when the slope was 15 °. Meanwhile, the average error for the physical terrain correction method was -5.6 meters even for the slopes up to 30 °. Thus, it is suitable to retrieve tree height for areas with up to 10 ° slopes using the direct method. However, a simple physical slope correction could be used in areas with greater slopes. This work enhances our understanding of the interactions between surface topography, forest structure and waveform shape.