Upper panels: estimated altitude distributions for Arecibo, PFISR, and MU at different degrees of aspect sensitivity from θ_s = 50° to 90°. The radar target volume sizes were set to 20% of the mean free path (L = 5). Lower panels: contour plots for the solution space of α and (β + γ) pairs for the fitting of the modeled altitude distribution to radar measurements for the case L = 5 and θ_s = 70°.