The use of ERS-1 SAR data in snow melt monitoring

ERS-1 SAR data, airborne data and in situ snow data were acquired for the Sodankyla test site in northern Finland for the winters of 1991-1992 and 1992-1993. The test area consists of sparsely forested areas (pine, mixed forests, and mires) and open areas (bogs, lakes, clear-cut areas, and urban area). A set of multitemporal ERS-1 SAR images covering the two winters have been analyzed and the results have been compared with in situ surveys and a digital land-use map. The results indicate that even in the presence of forest canopies (1) wet snow can be distinguished from other soil/snow conditions (dry snow and bare ground), and (2) snow melt maps can be derived from SAR images. Snow-melt maps indicate areas fully covered with wet snow, partly melted areas and snow-free areas.