NET RADIATION FLUX OVER SUB-ARCTIC SURFACES

Abstract

Some years ago, a series of maps of cover types in Labrador-Ungava was prepared at McGill University. These maps show the distribution of surfaces which have obvious wide variations in albedo and evaporative characteristics. By determining the albedo and evapotranspiration of these types, the maps permit estimates to be made regionally over the whole peninsula. This provides data on energy partitioning near the ground, which is important in forecasting stability and low-level turbulence and is useful for forecasts of ground moisture conditions. Evapotranspirometers and atmometers are run at Knob Lake (54°48?N?66°49?W) during the growing season, and short-wave radiation is measured continuously. Albedo is measured from the air, and different sites have been used for measurements of net radiation flux, using a portable ?economical net radiometer? developed by Suomi and Kuhn. The use of this instrument is described, and the results of the net flux measurements are discussed, with their relationship to total incoming short-wave radiation, evapotranspiration and latent evaporation.