Snow Water Equivalent retrieval using L- & C-band InSAR.

Interferometric Synthetic Aperture Radar (InSAR) imagery is a promising technique for retrieving Snow Water Equivalent (SWE). It exploits the relation of the interferometric phase to the amount and density of the snow in the radar signal path, leading to a quasi-linear relation with SWE (Guneriussen et al., 2001; Leinss et al., 2015). Here, we analyze timeseries of Sentinel-1 and ALOS-2 interferometric image pairs, collected over a test site in Sodankylä, Northern Finland, during the winter of 2019-2020. The satellite imagery is complemented by tower-based SAR observations using SodSAR (Sodankylä SAR) a 1-10GHz fully polarimetric SAR instrument. Typical satellite visit times (7 and 14 days) are compared with the 12-hour temporal resolution provided by SodSAR. Interferometric pairs from the three sensors are generated, and the interferograms are used to estimate the increase in SWE between the image acquisitions. Retrieved SWE is compared with measurements of an in-situ SWE scale, as well as manual ground observations made in the area. Coherence conservation and its relation with various meteorological events are also analyzed.