Surface slope and roughness measurement using ICESat/GLAS elevation and laser waveform

Surface slope and roughness are important geomorphological variables which have been used in the Earth and planetary sciences to infer material properties. For the ICESat/GLAS measurement, roughness and slope are two surface properties for broadening the width of the returned pulse. Based on this, a new method (GLAS waveform-derived roughness, GWR in short) is investigated to invert roughness from waveform broadening after excluding slope effect. Surface slope is estimated from the repeat tracks elevation of ICESat/GLAS, which is verified to be coincidence with geography facts (Landsat-7 images). Extensive experiments are performed using the proposed methods to evaluate the performance of surface properties (roughness, slope and elevation) in the Jakobshavn area. The experimental results demonstrate that, compared with the elevation-derived roughness method (GER in short), GWR is more sensitive to local surface properties in the gentle slope zone because it is a small-scale estimation. Additionally, GWR is a more stable roughness estimation which is immune to a strong elevation change.