Estimation of Glacier Ice Extinction Coefficients using Long-Wavelength Polarimetric Interferometric Synthetic Aperture Radar

Abstract

In recent years there has been increased interest in using synthetic aperture radar (SAR) to study glaciers for climate change research. Extensions to SAR such as polarimetric interferometric SAR (Pol-InSAR) offer additional potential in quantifying glaciological parameters such as the extinction coefficient. Extinctions are useful in characerising regions in increased volume scatter, which are related to the presence of ice structure. In this thesis a new scattering model relating long-wavelength Pol-InSAR observables to the ice extinction coefficient is proposed. Pol-InSAR coherences are modelled as a combination of a surface contribution (from the snow-firn interface and wind-induced sastrugi features) and a volume response. Surface-to-volume scattering ratios derived from a novel polarimetric decomposition are used with Pol-InSAR coherences to invert the extinction of the ice volume. The inversion is performed on airborne Pol-InSAR data at L-band and P-band frequencies acquired by DLR's E-SAR system over the Austfonna ice cap in Svalbard. Extinction dependencies on frequency and glacier zone are investigated, and validation is pefromed comparing ground penetrating radar data and airborne sounder data to extinction values.