Antarctic snow-covered sea ice topography derivation from TanDEM-X using polarimetric SAR interferometry

• Main Authors: Huang, Lanqing, Fischer, Georg, Hajnsek, Irena
• Format: Text
• Language: English
• Published: 2021
• Subjects: Antarctic; Weddell; Weddell Sea; Antarc*; Antarctica; Sea ice
• Online Access: https://doi.org/10.5194/tc-2021-157; https://tc.copernicus.org/preprints/tc-2021-157/

Single-pass interferometric synthetic aperture radar (InSAR) enables the possibility for sea ice topographic retrieval despite the inherent dynamics of sea ice. InSAR digital elevation models (DEM) are measuring the radar scattering centre height. The height bias induced by the penetration of electromagnetic waves into snow and ice leads to inaccuracies of the InSAR DEM, especially for multi-year sea ice with snow 5 cover. In this study, an elevation difference between the satellite-measured InSAR DEM and the airborne-measured optical DEM is observed from a coordinated campaign over the western Weddell Sea in Antarctica. The objective is to correct the penetration bias and generate a precise sea ice topographic map from the single-pass InSAR data. With the potential of retrieving sea ice geophysical information by the polarimetric-interferometry (Pol-InSAR) technique, a two-layer plus volume model is proposed to represent the sea ice vertical structure and its scattering mechanisms. Furthermore, a simplified version of the model is derived, to allow its inversion with limited a priori knowledge, which is then applied to a topographic retrieval scheme. The model-retrieved performance is validated with the optical DEM of the sea ice topography, showing an excellent performance with root-mean-square error as low as 0.22 m. The experiments are performed across four polarizations: HH, VV, Pauli-1 (HH+VV), and Pauli-2 (HH-VV), indicating the polarization-independent volume scattering property of the sea ice in the investigated co-polarized data.