Relation between Solar Radiation Income and Cloud Type in the Arctic

Abstract

Cloud amount and duration of sunshine are generally used to estimate direct and diffuse solar radiation income at the ground, where radiation instruments are not available. This method has serious drawbacks and a consideration of cloud type is also necessary. The different elements required for the calculation of radiation income at the ground are discussed. Such calculation can give only general results, and measured values of radiation in the Arctic, with different cloud types, are therefore examined and presented. The magnitude is discussed of the values in the Arctic of albedo of cloud tops, ground albedo, and the effect of composite cloud types. From the results it is possible to construct tables which show the depletion factor with 10/10 could cover for different combinations of cloud type frequencies. These tables make it possible to obtain approximate radiation income with mean overcast conditions, provided that the clear key radiation is known. The results are applicable to the Polar Ocean and Arctic Coast only.