Permittivity distribution determined by the CH2 data during the first 31 lunar days. The colour bar represents the relative permittivity values. The sites of 31 lunar days are indicated by the numbers at the top of the panel. (a) Permittivity distribution calculated by our method, where black dashed lines depict the boundary of the reflectors, and white dashed lines P₁–P₄ show the positions of permittivity profiles of the four vertical distribution in b−e. b−e Detailed permittivity varying with depths at a single horizontal position, located at x = 60, 360, 450, and 600 m, respectively. The grey horizontal dashed lines in b−e are the time values of the intersections between the four profiles (P₁–P₄) and reflector boundaries shown in a. The comparison of permittivity with Dong et al. (2020b) and Li & Zhang (2021) at x = 60 m, as shown in b.