Approach to the assessment of ground surface temperature under snow cover based on measurements in Svalbard

Ground temperature in winter is one of important parameters for evaluating the functioning of natural and technical systems. This temperature is formed under the influence of two factors – the air temperature and snow cover properties. At the same time, it is not always possible to measure the temperature of the ground during the cold season. A simple and easily available method has been developed to estimate the surface temperature from thickness of the snow cover and the air temperature. Based on mathematical modeling, numerical experiments were carried out to determine the temperature regime of the ground under the snow cover using different values of snow thickness, the snow density and the air temperature. The mathematicalmodel was tested against data of measurements of the dynamics of ground freezing in the area of the Barentsburg weather station in Western Svalbard. The ratio of snow density and its thickness was analyzed and the most common pairs of values of these parameters for snow thickness/density were obtained: 1/290; 0.75/270; 0.5/250; 0.3/200 m/(kg/m3). The results of numerical experiments made it possible to determine the temperature of the ground under snow and to calculate the relationship between the air and the ground temperatures. It was found that when the air temperature changes within the range from –20 to –40 °C, this ratio practically does not depend on the air temperature, but only on the parameters of the snow cover. With a snow thickness of 1 m, the ratio is 0.435 and 0.286 at air temperatures of –10 °C and –20 ... –40 °C, respectively. As a result, dependencies for calculating the difference between the temperature of the ground under snow and air temperature on the height of the snow cover and atmospheric air temperature have been obtained. Calculations have shown that this difference is 12.8 and 4.5 °C with a snow cover height of 0.5 m and an air temperature of –20 and –10 °C, respectively. Influence of snow density, soil moisture and the summer air temperature upon the ground surface temperature was estimated. The calculations of ground surface temperature were verified using measured data from Western Svalbard.