Geoscience Laser Altimeter System waveform simulation and its applications

To study the relationship between surface topography and satellite laser altimetry waveform, a numerical model that simulates an ideal satellite laser altimeter has been developed. It has a Gaussian beam pattern and a Gaussian pulse shape. Different three-dimensional surface topographies have been used in the simulation to generate waveforms. Using a non-linear least-squares method, the generated waveforms were fitted to theoretical models to calculate surface roughness and surface slope. The outputs from the models were then compared with the values calculated from the given assumed surfaces. There is no way to distinguish between a horizontal, randomly rough surface and a smoothly sloping surface from waveform fitting alone. However, if either the surface roughness or the surface slope can be acquired independently, the other one can be determined through waveform fitting.