Alpine Snowpack Refractive Index Retrieval Based on Tomograms Distortion Calculation

This letter introduces an iterative technique for estimating the refractive indices of a multilayered snowpack. It is based on minimizing the difference between the tilt observed in a TomoSAR image, assuming free-space propagation, and the one obtained using a developed analytical modeling approach. This minimization is carried out using particle swarm optimization (PSO) algorithm, and the subsequent approach applies an analytical modeling method that combines geometric principles and Snell–Descartes law to relate the apparent positions of scatterers to their real positions. In addition, it takes also into account the transmitting and receiving antenna coordinates and medium properties such as thickness and wave propagation velocity. This study is further enhanced by calculating cumulative and normalized intensities, coherence, and phase center. This analysis offers valuable insights into the depth of penetration and the layers that prevent the electromagnetic waves propagation from penetrating them.