The depth of the thermal influence zone of the surface in the snow cover

Abstract

The subject of the study is the snow cover, which determines the formation of the thermal regime of soils in winter. The purpose of the work is to determine the depth of the zone of thermal influence of the surface in the snow cover. That is, the determination of the zone of temperature fluctuations (daily, decadal) in the snow cover when the temperature of the atmospheric air changes. Determining the depth of this zone is important both for taking into account the formation of the properties of the snow cover itself, and for choosing a method for modeling the process of thermal interaction of the atmosphere with the ground in the presence of snow cover. In particular, the possibility of taking into account snow cover as thermal resistance in modeling thermal processes. To assess the depth of thermal influence, the well-known Goodman formula was used, obtained by solving the corresponding problem of thermal conductivity by the integral method and representing the dependence of the depth of the zone of temperature change in a solid with an abrupt change in surface temperature on time and thermal conductivity of the material (in this case, snow of a certain density). To determine the thermal conductivity, the formulas of Abels and Osokin were used to determine the thermal conductivity coefficient of snow depending on density. At the same time, it was taken into account that the density of snow cover is a variable in depth, determined by the linearized Abe formula. Alternatively, a snow cover with a density equal to the average integral density in depth is considered. Dependences are obtained to determine the duration of the attenuation period of surface temperature fluctuations at a certain depth of snow cover. An indicator of the change in the depth of vibration attenuation (the depth of thermal influence) is proposed. To assess the effect of snow reclamation, a formula is proposed that allows us to determine the degree of change in the duration of the period of complete attenuation of temperature in depth during compaction of snow cover, depending on the compaction coefficient. A dependence has been obtained linking the depth of the zone of thermal influence with the duration of the period of daily temperature fluctuations on the surface of the snow cover and its density. Comparison of the calculated data according to the obtained formulas with the data on the depth of attenuation of daily temperature fluctuations in snow cover with different snow densities, given in the literature, showed good convergence. This allows us to recommend the obtained formulas for practical use in assessing the process of formation of the thermal regime of snow cover.