Snow cover and surface albedo in Estonia

Abstract

The paper reviews the investigations into snow cover and surface albedo in Estonia. The albedo has been determined by an indirect method using the relationship between the albedo and the snow cover duration in the Tartu-Toravere Actinometric Station over the whole Estonian territory. The parameters of snow such as the duration of snow cover, snow depth and surface albedo show noticeable differences within the range of Estonia: on the islands, in the coastal areas and the Central-Estonia plain their values are lower than in the Pandivere and Haanja uplands and have decreased everywhere over the time span 1962 to 1995. At the same time the areal variability of snow cover duration and surface albedo have increased in Estonia. The snow cover duration is changed above all on the islands, in the western coastal areas and in the Central-Estonian plain. During the observation period the annual duration of snow cover has decreased by 30 days, snow depth by 17 cm. Noticeably decreased by 0.032 is the mean annual surface albedo for the entire Estonia. Changes are most conspicuous in February and March. In March, snow cover duration has decreased by 12 days, snow depth by 3-4 cm, and surface albedo by 0.23. Reduced snow cover and surface albedo in late winter and early spring, caused by increased temperature, strongly intensifies absorption of solar radiation at the surface and thereby leads to an additional increase in air temperatures near the surface. If founded trends continue the climate will change dramatically in Estonia.