Maximum Surface Albedo of Seasonally Snow-Covered Lands in the Northern Hemisphere

Abstract

Areally weighted clear sky surface albedo of snow-covered land in the middle and high latitudes of the Northern Hemisphere was measured from satellite imagery in A 1?1° latitude-longitude cells. The study area included 87% of the land polewards of 25°N, where Dickson and Posey found the probability of the seasonal occurrence of snow cover over ?2.5 cm deep to be greater than zero. Albedo is 0.60 in Eurasia and 0.56 in North America, approximately 3.5 times greater than snow-free conditions. The highest average value for a 5° latitudinal zone is 0.77 at 70?75°N. The lowest is 0.43 at 60?75°N, which includes 0.36 in Eurasia and 0.58 in North America. The low albedo is due to the masking of snow covered ground by the canopy of coniferous forests. Data were obtained by image processor analyses of Defense Meteorological Satellite Program imagery. Scene brightness was converted to surface albedo by linear interpolation between bright and dark snow-covered surfaces with known albedo. The resulting chart is a refinement of an earlier product. The 1 ? 1° digital data set is available for use in climate modeling.