Changes in Snow Cover Characteristics Over the Russian Territory in Recent Decades

The state of snow cover is one of the most important characteristics of the Northern Eurasia climate. The present work sheds light on the snow variations by using empirical and statistical analysis of time series of daily snow depth over Russia. For 400 Russian stations, time series of the daily snow depth and of the extent to which the near-station territory is covered by snow have been prepared in RIHMI-WDC for the period 1951-2006. Our analyses revealed the following regional features in the change of snow cover characteristics. Increases in winter precipitation and surface air temperature affected the variability of snow characteristics. In particular, tendencies towards the increase in the average snow depth over the Russian territory are prevailing, while only a few Russian regions show a decrease in winter snow depth. The largest variations in the average snow depth occur in the late winter - early spring period. In the recent three decades a substantial part of the Russian territory exhibits a shorter snow-cover period. The regionally-averaged snow cover characteristics were analyzed across the seven quasi-homogeneous climatic regions of Russia as well as for the entire nation. In the European part of Russia and in the Russian Far East, the increase in the average snow depth is controlled by winter and autumn precipitation growth. Time series of the number of days with different snow depths have been derived from daily snow depth observations. In the past decades, the number of days with the snow depth above 1 cm tends to decrease in the west of European Russia, in the Urals, Siberia and the Chukotka Peninsula (i.e., over most of Russia), while the number of days with significant snow depth (above 20 cm) tends to increase slightly. Taking into account that the Russian territory dominates the snow-covered areas of Eurasia, we conclude that across most of Northern Eurasia the snowy season became shorter but more "intense".