Studying the heterogeneity of the lunar regolith at the Chang’E-4 landing site. Both the radar observation and the simulation were normalized with their peak value of the surface reflection echo. (A) The RMSE value is a function of the disturbance range (DR) for the radar trace of 8910. (B) Comparison between the radar simulation and observation for which the disturbance range is 0.22 m, (C) 1 m, and (D) 2 m, where the black dashed curve and the solid red curve show the radar observation and simulation, respectively. (E) The statistical result of the disturbance range.