Spatial heterogeneity of albedo over a snow-covered agricultural landscape

Measurements of albedo were obtained along a 100 km transect in east central Illinois using a combination of airborne and ground-based radiometers. Analysis of the measurements focused on three different land use categories: agricultural cropland, prairie grass, and woodland. The value of albedo over the woodland after a fresh snowfall was 0.30, which is somewhat higher than what has been measured in a previous experiment over an aspen forest but similar to previous measurements over a deciduous forest in the eastern United States. The albedo values over the grassland were similar to past experiments and similar to the values over cropland. The drifting that accompanied one of the snow events caused large differences in albedo during snowmelt compared to another event with minimal drifting but similar average snow depth. The albedo was lower over the melting wind-blown snow cover than for a snow cover of similar average depth that fell under light wind conditions. These large differences suggest that inclusion of meteorological conditions during snowfall in snow parameterizations may appreciably increase their accuracy. Different tillage practices used in the agricultural fields also caused measurable differences in albedo during the snowmelt phase.