Discrimination analysis of wet and dry snow covers from RADARSAT SAR data

摘要

This paper focuses on the discrimination between wet and dry snow covers from active microwave data. The backscattering coefficients were extracted from two images of the RADARSAT SAR (Synthethic Aperture Radar) sensor acquired in the standard mode S7 (45°- 49°), during the winter and the spring of 1997. The discrimination analysis is performed in both standard modes S1 (20°-27°) and S7 (45°-49°), using simulation results of the wet snow signal. The latter conducted for several wet snow dielectric and structural properties at the air-snow interface are then compared to the measured dry snow signal. Based on a radiative transfer model, the results show the ability of the S1 mode to provide a good discrimination for wet snow surface characterized by rms height ≤ 5 mm and volumetric snow liquid water content > 1. For the S7 mode, optimal discrimination requires rms height ≤ 7 mm and volumetric snow liquid water content ≥ 3. It is also shown that, the difference between the signal of dry and wet snow decreases with wet snow surface roughness, more so over sparse-forested areas.