Changes in snow cover and surface albedo in Estonia during the last 100 years

Abstract

The year-to-year changes of the snow cover and the albedo in late winter and early spring as climatic factors are studied. The dependence of the surface albedo on the duration of snow cover recorded at the Tartu Actinometric Station in 1953-1992 has been used for a reconstruction of the late winter - early spring albedo from 1892 to 1992 for the Tartu area. Similarly the albedos for 39 meteorological stations and posts in Estonia were reconstructed for the period 1951-1990. The duration of the snow cover had shortened by about 17 days in Tartu, most of the decrease having occurred during the past 40-50 years. The decrease in the late winter - early spring surface albedo during the last 101 years amounted to 0.11. In some areas of Estonia the shortening of the duration of the snow cover has amounted to 22 days. The shortening has been most pronounced over a belt through Central Estonia (Virtsu-Paunkula-Kastre), at Lake Peipsi and in the elevated areas. The albedo has decreased by 0.12. Years without snow and with a low albedo have become more frequent in the latest 20 years. These changes may have had an effect on near-surface temperatures in spring and in summer