VARIATIONS IN THERMAL DIFFUSIVITY OF THE TUNDRA COVER ACCORDING TO THE DATA OF FIELD OBSERVATIONS DURING THE SUMMER PERIOD
S.G. Kornienko
Oil and Gas Research Institute, RAS, Gubkina str. 3, Moscow, 119333, Russia
Keywords: thermal diffusivity, land cover, tundra, air temperature, humidity
Abstract
Thermometric observations in the area of the Yamburg oil and gas condensate field in summer have been used to calculate the thermal diffusivity (K) coefficients of moss (Sphagnum fuscum), bushy lichen (Cladonia arbuscula), and two-layer samples of soil-vegetation cover, consisting of mixed vegetation (Empetrum nigrum, Vaccinium vitis-idaea, Carex arctisibirica) of different thickness and sandy soil. The thermal diffusivity for sphagnum moss and lichen have been calculated for the periods with different meteorological conditions. The K values, obtained during the experiment, are quite close to the previously published values of the thermal diffusivity for similar types of the land cover. An amplitude of daily temperature fluctuations at a depth of 12 cm under the cover samples decreases by 84-94 %. The amplitude of fluctuations decreases by 37 % in the upper layer of the cover with a thickness of 4.2-6.4 cm, depending on a type of the cover. An abnormally high increase in the thermal diffusivity of sphagnum moss was noted with an increase in air humidity and precipitation by the end of summer. This fact confirms the unique thermal insulation properties of sphagnum moss, which ensure the conservation of ice wedges in drained areas. It was found that at average daily air temperatures below 27 °C and relative air humidity above 49 %, the K values of the studied samples of the land cover can serve as indicators of their thermal insulation properties.
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