Monitoring snow depth and its change using repeat-pass interferometric SAR in Manas River Basin

Snow depth is one of the most important parameters for hydrological applications. SAR (Synthetic Aperture Radar) has the ability to monitor the surface deformation effectively, with a certain penetration and interference measurement capability. The refraction of microwaves in dry snow is shown to have a significant effect on the interferometric phase. According to this, snow depth estimation with repeat-pass InSAR (Interferometic SAR) measurement by using ENVISAT ASAR IMS products was proposed. Taken pediment plain in Manas river basin as study area, the optimal InSAR pairs (with and without snow) were chosen, and then the interferometric phase was calculated as a product of InSAR optimized processing. And local incident angle was used to improve the final snow depth estimated result as a substitution of satellite incident angle 23°. From snow depth estimated results between Jul. 2008 and Feb. 2009, it was pictured that the average snow depth is about 20cm in study area, which is consistent with the field survey results. Lastly, error evaluation was proposed to unreasonable estimation results, and also some reasons to cause inaccuracy were discussed: decoherence due to snow cover and atmospheric effects; two input parameters: local incident angle in SAR with snow may have changed because of snow distribution, and snow density varies as snow metamorphism and hierarchy in a whole study area.