Influence of Intra-seasonal Snowfall Deposition, the Peculiarities of Snow Cover Accumulation and Winter Season Temperature Variation on Ground Freezing Depth

On basis of the data of winter seasons on snowfalls, thermal regime and peculiarities of snow accumulation regime and according to the calculating scheme with three-layer media heat conductivity problem (snow cover, frozen and thawed ground) and with phase transition on the boundary of frozen and unfrozen ground with daily resolution the estimation of ground freezing depth for the North-East part of European territory of Russia for the period of 1988–2008 was conducted. The Heat balance equation included phase transition energy, inflow of heat from unfrozen ground and outflow to frozen ground, snow cover and atmosphere. The heat flux was calculated on basis of Fourier law as a product of heat conductivity and temperature gradient. The assumption that snow cover consists of different layers deposited by different snowfalls and having different structure and density and heat conductivity depending on its density was taken. The density and heat conductivity of each layer and the whole thickness of snow cover were determined and the regional stratigraphic column for snow cover was compiled and the calculation of ground freezing intensity and freezing depth was conducted. The comparison of estimated with calculating scheme and observed values of ground freezing depth were performed and the correlation of equal 0.76–0.77 of them was stated.