Change in the thermophysical properties of snow cover during compaction

The purpose of the work is to determine the degree of change in the thermophysical characteristics of the snow cover during compaction. A new indicator, the “snow cover compaction coefficient”, has been introduced. The dependences of the change in the main characteristics of the snow cover on the compaction coefficient have been obtained. The change in the following characteristics has been considered: thermal conductivity, thermal diffusivity, thermal resistance, thermal inertia, thermal stability, and the Fourier and Stefan criteria. A summary table has been constructed, which makes it possible to determine the form of relationship between the above main characteristics and the compaction factor. It has been established that the form of functional relationship between the thermal conductivity coefficient and the snow density plays a crucial role in the quantitative relationship between the characteristics and the compaction factor. For example, if we assume a linear relationship between the thermal conductivity coefficient and the density, the degree of reduction in thermal resistance during snow reclamation is proportional to the square of the compaction factor, while if we assume a parabolic relationship between the thermal conductivity coefficient and the density, the degree of reduction in thermal resistance is proportional to the third power of the compaction factor. The values of the considered thermophysical parameters are obtained from the compaction factor for the case of the dependence of the thermal conductivity coefficient λ on the snow density ρ in the form of a truncated polynomial of an arbitrary degree n. Graphical dependencies of individual indicators on the form of initial functional relationships of the initial values obtained theoretically and from experimental studies and field observations are presented. It is also shown that the percentage discrepancy in the calculation results caused by the choice of exponential function of the thermal conductivity coefficient on density increases for almost all of the thermal properties with an increase in the value of the compaction coefficient and considerably exceeds the value allowed in engineering calculations. For example, the discrepancy of thermal resistance of snow cover when the compaction coefficient is 2.0 is 50 %, and with compaction coefficient equal to 4.0 it is 75 %. The main quantitative relationships of change in thermal conductivity coefficients of snow and thermal resistance of snow cover depending on the compaction degree has been formulated.

snow cover, snow reclamation, thermal properties, snow density, compaction coefficient, quantitative functions/relationships