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 1991-19 92 and 1992-1993, The test area consists of sparsely forested areas (p ine, mixed forests, and mires) and open areas (bogs, lakes, clear-cut areas, and urban area), A set of multitemporal ERS-1 SAR images coveri ng the two winters have been analyzed and the results have been compar ed with in situ surveys and a digital land-use map, The results indica te that even in the presence of forest canopies 1) wet snow can be dis tinguished 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 sn ow-free areas.