Earth’s Cryosphere, 2022, Vol. XXVI, No. 1, p. 9-18.

VARIATIONS IN THERMAL DIFFUSIVITY OF THE TUNDRA COVER ACCORDING TO DATA FROM FIELD OBSERVATIONS DURING THE SUMMER PERIOD

S.G. Kornienko

Oil and Gas Research Institute, Russian Academy of Sciences, Gubkina str. 3, Moscow, 119333 Russia; spaceakm2@ogri.ru

Summer thermometric observations in the area of the Yamburg oil and gas condensate field have been used to calculate thermal diffusivity of moss (Sphagnum fuscum), shrubby lichen (Cladonia arbuscula), and two-layer samples of soil-vegetation cover consisting of mixed vegetation (Empetrum nigrum, Vaccinium vitis-idaea, Carex arctisibirica) of varying thickness and sandy soil. For sphagnum and lichens, thermal diffusivity has been calculated for the periods with different weather conditions. Thermal diffusivity values obtained during the experiment are quite close to the previously published data on similar types of the tundra cover. At a depth of 12 cm, the amplitude of daily temperature fluctuations under the vegetation cover decreases by 84–94 %. Its decrease by 37 % takes place in the upper layer of the tundra cover of 4.2–6.4 cm in thickness in dependence on the type of the cover. An abnormally high increase in thermal diffusivity of sphagnum moss takes place upon an increase in air humidity and precipitation at the end of summer. This fact confirms the unique thermal insulation properties of sphagnum moss providing conservation of ice wedges in the areas of drained sediments. At the mean daily air temperatures below 27 °C and relative air humidity above 49 %, the thermal diffusivity of the studied samples of the soil-surface cover can serve as an indicator of their thermal insulating properties.

Thermal diffusivity, soil-vegetation cover, tundra, air temperature, water content