Landsat Thematic Mapper (TM) Derived Reflectance from a Mountainous Watershed during the Snow Melt Season

Landsat-5 Thematic Mapper (TM) reflectances recorded i May 1989 from a mountainous catchment at Kvikne, Norway, are analyzed and compared with simultaneously measured in situ albedo. The satellite-registered shortwave snow albedo comparable to bare ground albedo and as low as 0.19 was found in areas where the snow was highly metamorphosed and heavily blackened by organic material. However, the contrast between snow and snow-free areas can be strongly improved by using a normalized TM Band 2-5 difference image. While TM Band 2 shows varying degrees of snow surface contamination within the study area, the normalized TM Band 2-5 difference image is not affected by impurities. Further, a normalized TM Band 2-4 difference image indicates that about one third of the variability in TM Band 4 is caused by effective snow grain size variations while the remaining is a result of surface contamination. Finally, the satellite reflectances have been corrected for atmospheric absorption and scattering present on the day of the satellite overpass.