Synergistic Use of Satellite Laser Altimetry and Shuttle Radar Topography Mission DEM for Estimating Ground Elevation Over Mountainous Vegetated Areas

Topography is fundamental to numerous environmental studies for understanding Earth surface processes. With a near global coverage, satellite lidar Geoscience Laser Altimeter System (GLAS) onboard Ice, Cloud, and land Elevation Satellite (ICESat) provides valuable terrain elevation information via Gaussian decomposition of its waveforms. It is commonly assumed that the lowest decomposed Gaussian peak corresponds to terrain surface. Although this assumption is valid over flat areas with sparse canopy, it might be problematic over sloped areas with surface objects. This letter proposes a new algorithm to estimate ground elevation over mountainous vegetated areas using GLAS data in conjunction with Shuttle Radar Topographic Mission Digital Elevation Models (SRTM DEMs). It was found that incorporating SRTM DEM can reduce the bias of the mean ground elevation estimates by up to 1-3 m. This letter also suggests that more research is needed for improving ground elevation estimates over mountainous areas with relatively open canopy.