Monitoring the Dynamics of an Alpine Glacier using TanDEM-X Dual-Pol SAR Data

Abstract

Snow and ice masses form a major part of the Earth cryosphere. As the primary source of fresh water within our ecological environment, snow and ice play an essential role in the climate system with severe impact also on the society and the economy. In the last decades, space-borne radar remote sensing has led to significant developments in the field of glaciology, due to the large spatial coverage with a relative short revisit time and a high spatial resolution. Thanks to the penetration capability of microwaves into dry snow and ice, conventional SAR is sensitive to surface features as well as to the subsurface structure of glaciers and ice sheets. In additions, polarimetric SAR (PolSAR) allows to gain information about different scattering mechanisms as well as geometric and dielectric properties of the scatterers. This study investigates the potential of dual-polarimetric TanDEM-X time series data to monitor the temporal surface dynamics of the Aletsch glacier, in the Swiss Alps. In a first step, the sensitivity of a set of PolSAR indicators is assessed with respect to the different ice zones and to the seasonal and multiannual dynamics of the glacier. The second part of the study is focused on the analysis of polarimetric phase differences for the detection of snowfall events, which represent a primary contribution to the glacier mass balance. For this, a propagation model is employed which links phase differences to snow microstructure. The results of this study further confirm the uniqueness of polarimetric SAR for glaciological studies, as well as the need of further efforts to access its underexploited potential.