Spatial heterogeneity of albedo over a snow-covered agricultural landscape

Measurements of albedo were obtained along a 100 km transect in east centra l Illinois using a combination of airborne and ground-based radiometers. An alysis of the measurements focused on three different land use categories: agricultural cropland, prairie grass, and woodland. The value of albedo ove r the woodland after a fresh snowfall was 0.30, which is somewhat higher th an what has been measured in a previous experiment over an aspen forest but similar to previous measurements over a deciduous forest in the eastern Un ited States. The albedo values over the grassland were similar to past expe riments and similar to the values over cropland. The drifting that accompan ied one of the snow events caused large differences in albedo during snowme lt compared to another event with minimal drifting but similar average snow depth. The albedo was lower over the melting wind-blown snow cover than fo r a snow cover of similar average depth that fell under light wind conditio ns. These large differences suggest that inclusion of meteorological condit ions during snowfall in snow parameterizations may appreciably increase the ir accuracy. Different tillage practices used in the agricultural fields al so caused measurable differences in albedo during the snowmelt phase.