Determining snow depth using airborne multi-pass interferometric synthetic aperture radar

Abstract

Snow accumulation is a significant factor for hydrological planning, flood prediction, trafficability, avalanche control, and numerical weather/climatological modeling. Current snow depth methods fall short of requirements. This research explores a new approach for determining snow depth using airborne interferometric synthetic aperture radar (InSAR). Digital elevation models (DEM) are produced for Snow Off and Snow On cases and differenced to determine elevation change from accumulated snow. Interferograms are produced using Multi-pass Single Look Complex airborne Ku-band SAR. Two approaches were attempted. The first is a classical method similar to spaceborne InSAR and relies on determining the baseline of the interferometric pair. The second used a perturbation method that isolates and compares high frequency terrain phase to elevation to generate a DEM. Manual snow depth measurements were taken to verify the results. The first method failed to obtain a valid baseline and therefore failed. The second method resulted in representative DEMs and average snow depth errors of -8cm, 95cm, -49cm, 176cm, 87cm, and 42cm for six SAR pairs respectively. Furthermore, Ku-band appeared to be a high enough frequency to avoid significant penetration of the snow. Results show that this technique has promise but still requires more research to refine its accuracy.