Evaluation of the single reference image snow-covered area estimation method for the boreal forest zone

Spaceborne Synthetic Aperture Radar (SAR) data have been utilized for regional scale snow-covered area (SCA) monitoring for several years. Different methods have been developed and demonstrated for different geographical regions. A method utilizing a single reference image for SCA estimation has been shown to function well on mountainous and non-forested regions. For the boreal forest zone a method using two reference images and a forest compensation procedure has been previously utilized. The single reference image method is evaluated here for the boreal forest zone and its performance is compared with the Helsinki University of Technology (TKK) SCA method that is specifically developed for boreal forest regions. The SCA evaluations are carried out using Radarsat-1 data for the snow-melt seasons of 2004-2007. The SCA estimation accuracies for the radar-based methods are determined using optical satellite based SCA data as reference. The results show that SCA estimation using a single reference image is usable for the boreal forest zone, although the accuracy is significantly weaker than that of the TKK-developed, boreal forest specific SCA method. The best accuracy obtained shows a root-mean-square error (RMSE) of 0.176 for the single reference image method and an RMSE of 0.123 for the TKK SCA method.