firn characterization, scattering signal component, radio‐echo sounding, Surface roughness, Ice, Glaciers, Stratigraphy, Scattering, Correlation, Radar data, Backscattering, Roughness, Spatial discrimination, Airborne sensing, Echoes, Heterogeneity, Elevation, Roughness effects, Polar environments, Radar, Layers, Surface roughness effects, Echo sounding, Bac...