Dual-Frequency Airborne SAR Campaign on Snow Mass Retrieval for High-Alpine Terrain

Abstract

(1) The Wörgetal campaign, based on L- and C-band SAR data, confirms the high potential of the Repeat Pass InSAR approach for observing snow accumulation at high spatial resolution. The L-band InSAR data show high coherence and good performance for SWE retrieval also for high snow accumulation events. (2) C-band InSAR data show good results for retrieving snow accumulation of moderate intensity but are not well suitable for intense snowfall due to low coherence and 2pi phase ambiguity. (3) VV-polarized RP-InSAR data show slightly higher coherence than HH-polarized data, but the differences in retrieved SWE are not significant. (4) Delta-k interferometric processing is able to capture intense snowfall events and to cover extended time spans, an option for closing gaps in conventional RP-InSAR SWE retrievals. (5) Geostationary SAR offers short repeat observation intervals, of interest for obtaining continuous time series of snow accumulation. Further studies are needed to assess the impact of snowfall on SAR image formation and decorrelation. (6) Critical issues for InSAR SWE retrieval are: - limited to dry snow, - selection of reliable reference points for phase / SWE calibration, - reduced sensitivity in forests, - topography related gaps (to be filled by data from crossing orbits), - correction for atmospheric phase delay.