Thermal resistance of snow cover

The subject of the study is a snow cover consisting of an arbitrary number of layers of varying thickness and different snow densities. The thermal resistance of such a cover has been investigated. One of the key parameters in the study of the interaction of various engineering structures with snow is the thermal resistance of the snow cover. The aim of the work was to assess the accuracy of calculating the thermal resistance of a layered snow cover when averaging the snow density with depth. Two approaches to determining the thermal resistance of the snow cover have been considered: as a layered structure and as an equivalent homogeneous structure with a constant average density calculated as a weighted average. Classical formulas for determining the thermal conductivity coefficient based on the density of the snow cover—namely, the formulas by G.P. Abels and N.I. Osokin—were used for calculations of thermal resistance. A comparison of two calculation methods for computing the thermal resistance of the snow cover was carried out: as the sum of the thermal resistances of the layers and as a single-layer structure with weighted average density. The analysis of numerical and graphical data allowed for the following main conclusions. With a nonlinear relationship between the thermal conductivity coefficient and the snow density, the error increases with the increase in the compaction coefficient of one of the layers. For example, when the density of a layer doubles, the relative calculation error ranges from 20% to 30.0% and depends on the ratio of the thicknesses of the individual layers. It was established that when the compaction of one layer is less than 1.6 times, the use of the concept of "average snow cover density" in thermal calculations for determining the thermal resistance of the snow cover is quite acceptable. In this case, the error will not exceed the allowable value in engineering practice. With increased compaction, it is necessary to calculate the total thermal resistance of the snow cover as the sum of the thermal resistances of individual layers, as is customary in building thermal physics for determining the thermal resistance of enclosing structures. Further research should focus on determining the accuracy of thermal resistance calculations as the snow density depends on the layer thickness, as well as accounting for the influence of snow structure with constant density on the thermal conductivity coefficient. It is also of interest to compare these theoretical calculations with existing data from field observations.