Polarimetric SAR Signatures for Characterizing Geological Units in the Canadian Arctic

Abstract

This study investigates the polarimetric radar signatures of geological units in the Canadian Arctic to characterize their physical surface properties. It focuses on the Tunnunik and Haughton meteorite impact structures using RADARSAT-2 quad polarimetric synthetic aperture radar (SAR) data. The geological units show different three-dimensional (3-D) polarimetric SAR signature plots (i.e., radar backscattering responses according to the orientation and the ellipticity of a polarization state). We analyzed the quantitative relationship between the polarimetric SAR signatures of the geological units and their surface roughness. The pedestal height and the standard deviation of linear copolarization responses (SDLP) were calculated from the 3-D copolarization power signature plot, and then compared to in situ surface roughness measurements derived from LiDAR scanned high-resolution surface topography. The results show that the pedestal height has a positive correlation coefficient of ∼0.6 with surface roughness, while the SDLP has a negative correlation coefficient of ∼0.8 with surface roughness. The variation between the different polarization responses is highly dependent on the surface roughness of the geological units. The SDLP is thus suggested as a promising parameter to characterize surface roughness, in addition to the pedestal height that has been commonly used.