High-Performance Numerical Simulation of Radar Wave Scattering due to Topographic Roughness

This paper focuses on the study of the scattering of radar waves due to rugged topography relief. It is a helpful assistance to identify features in GPR reflection profile to separate true subsurface reflectors and artifacts caused by surface scatterers. Two examples are presented here to illustrate the approach. The first case is for a numerical simulation of the edge diffraction from rugged topographic relief on Earth. The other is one from the numerical model of the 60-MHz radar wave propagation to look into the edge diffraction caused by the impact crater depressions based on the real topography and stratigraphy of the lunar surface at the landing site of the 2014 Chinese lunar lander Chang'e-3. The purpose of this study is to explore the possibility to explain the featured events in the lunar penetration radar (LPR) profile recorded by the Yutu lunar rover, which were originally identified as subsurface reflectors from stratigraphic interfaces. It is noteworthy to point out that the 60-MHz radar system on the Yutu lunar rover uses the unshielded rod antennas. Substantial portion of the radiated energy is in the air above the lunar surface. The simulation of lunar radar wave propagation suggests that it is likely that the later time events in the 60-MHz LPR profile might be associated with the focused surface scattering waves from the edge of the impact craters near the Chang'e-3 landing site.