|
ИСТИНА |
Войти в систему Регистрация |
Интеллектуальная Система Тематического Исследования НАукометрических данных |
||
The Effect of Snow Hardness on Soil Freezingтезисы доклада
- Авторы: Sosnovsky A., Osokin N.
- Сборник: International Conference “Solving the puzzles from Cryosphere” : Program, Abstracts : Pushchino, Russia, April 15–18, 2019
- Тезисы
- Год издания: 2019
- Место издания: Москва
- Первая страница: 171
- Последняя страница: 172
- Аннотация: Effect of the snow thermal resistance on soil freezing is comparable to the influence of mean temperature in the cold period. The thermal resistance of snow cover depends on the thermal conductivity of snow. The scatter of snow thermal conductivity in 2-3 times arises from differences in the microstructure of snow at a given density. Our measurements have shown that average value of coefficient of efficient thermal conductivity of the depth hoar with density of 280 kg/m3 is 0.12 W/(m K) that in 3 times smaller than the same coefficient of granular frozen together snow with density of 370–390 kg/m3. The thermal conductivity of snow depends on the contacts between ice crystals. The larger the contact area, the better the heat transfer from one layer to another. But the strength characteristics of snow, and especially its hardness, depend on the bonds between ice crystals, so the thermal conductivity and hardness of snow depend on the structure of snow. Note, that measurements of snow hardness are less laborious than measurements of its thermal conductivity. The results of experimental investigation of thermal conductivity of snow on the Svalbard archipelago in the conditions of natural occurrence are considered. The observations were carried out in the spring of 2013–2015 in the vicinity of the meteorological station “Barentsburg”. The obtained data were processed using the Fourier equation of thermal conductivity. That allowed deriving relationship between thermal conductivity and snow hardness and determination of the coefficient of thermal conductivity of the snow with different structure and density. To verify the reliability of the approach to the determination of snow thermal conductivity, numerical experiments were performed on a mathematical model, which did show good convergence of the results. The obtained formulas for the coefficient of thermal conductivity of very loose, loose, medium and hard snow (according to the international classification of seasonal snow falls) are compared with the data of other studies. It was found that when the snow density is within the range 0.15–0.40 g/cm3 these formulas cover the main variety of thermal conductivity of snow. This allows estimating the coefficient of thermal conductivity and to determine the thermal resistance of snow cover in the field by measuring the density and hardness of different layers of snow. The thermal conductivity of snow with a density of 200 kg/m3 at different hardness varies by 3-4 times, for snow with a density of 300 kg/m3 - by 2.5 times and for snow with a density of 400 kg/m3 - by 1.7 times. The effect of the snow cover hardness on dynamics of the soil freezing is analyzed with the use of numerical modeling. Model calculations show that soil freezing depth differs by 2.9 and 2.1 times for snow of different hardness at a snow cover height 0.5 m and an average negative air temperature of –5 and -15 °C. With a snow cover height of 1 m, this ratio increases to 3-4 times. The results of calculations show that for a more accurate assessment of the depth of soil freezing it is necessary to take into account the structure of snow cover. The mathematical modeling was carried out according to the framework of fundamental scientific studies within the project reg. № 0148-2019-0004, field studies on Svalbard were conducted with financial support from the state assignment and logistical assistance of the Russian Scientific Center on Spitsbergen (RSCS), processing and analysis of experimental data was supported by the Russian Foundation for Basic Research, grant No 18-05-60067.
- Добавил в систему: Сосновский Александр Вульфович