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An increase in air temperature leads to a significant transformation of the relief and landscapes of the Arctic. The rate of permafrost degradation, posing a profound change in the Arctic landscape, depends on air temperature, vegetation cover, type of soils, surface and ground waters. The existing international circumpolar programs dedicated to monitoring the temperature state of permafrost TSP (Thermal State Permafrost) and active layer thickness CALM (Circumpolar Active Layer Monitoring) are not sufficient for a comprehensive characterization of geocryological conditions. Yet, no standardized protocol exists for permafrost monitoring and related processes. Here, we propose a novel multi-parameter monitoring protocol and implement for two sites in the European part of the Russian Arctic: the Yary site along the coast of the Baydaratskaya Bay in the Kara Sea (68.9°N) within the continuous permafrost area and the Hanovey site in the Komi Re-public (67.3°N) within the discontinuous permafrost one. The protocol includes drilling boreholes, determining the composition and properties (vegetation cover and soils), snow cover measure-ment, geophysical imaging, active layer estimation and continuous ground temperature meas-urements. Ground temperature measured in 2014 – 2020 revealed that amplitudes of surface tem-perature fluctuation had no significant difference between the Yary and Hanovey sites, while that the mean annual temperatures between the areas had a considerable difference of greater than 3.0 °C. The period of the presence of the active layer changed with the year (e.g., ranging between 135 and 174 days in the Yary site), showing longer when the air temperatures in summer and the preceding winter were higher. Electrical resistivity tomography (ERT) allowed determining the permafrost distribution and active layer thicknesses. Thermometry results were consistent with our geophysical data. Analyzing the composition and properties of frozen soils helped better interpret the data of geophysical and temperature measurements. Our work by integrating the study of the soil properties, ground temperatures, and ERT allowed fully characterize these sites, suggesting that it helps better understand the thermal state in any other research sites in the European north of Russia. Our suggested monitoring protocol enables calibrating and verifying the numerical and analytical models of the heat transfer through the earth’s surface.

ПРОГНОЗ ТЕМПЕРАТУРНОГО РЕЖИМА НАСЫПИ СЕВЕРНОЙ ЖЕЛЕЗНОЙ ДОРОГИ (В ТУНДРОВОЙ ЗОНЕ У СТАНЦИИ ХАНОВЕЙ) ПРОГНОЗ ТЕМПЕРАТУРНОГО РЕЖИМА НАСЫПИ СЕВЕРНОЙ ЖЕЛЕЗНОЙ ДОРОГИ (В ТУНДРОВОЙ ЗОНЕ У СТАНЦИИ ХАНОВЕЙ) The article presents the results of fi eld studies near Northern Railway embankment (Hanovey station) in fi eldwork area of Geocryology Department (Lomonosov Moscow State University), where performed: cone penetration test, measuring thickness of active layer of and soil temperatures, monitoring settlement of embankment, laboratory tests. Mathematical model was compiled in the Qfrost program based on these data taking into account the unevenness of the snow cover in the study area. Calculations of the temperature regime of the embankment until 2050, carried out taking into account climatic changes (according to the RCP 4.5 scenario), showed that the thickness of the talik at the embankment will increase 40% in 30 years and without taking this factor into account — 17%. The article also discusses the features of the position and structure of the embankment, the composition and properties of frozen soils, which signifi cantly aff ect the stability of the embankment.

The degradation of permafrost can induce geohazards such as thaw subsidence affecting the performance of railway infrastructures. For example, along an 800-m-long segment Russian North Railway (from Pesets to Hanovey railway station), some zones of thaw subsidence were studied in summer 2018. The subsidence can be as high as 0.5 m. Drilling, landscape zoning, near-field transient electromagnetic sounding, and electrical resistivity tomography were carried out to assess the underlying stratigraphy and permafrost conditions. Engineering and geological conditions of the site are complicated by the presence of permafrost. Soils can be in thawed and frozen state at the base of the embankment. The spatial arrangement of thawed and frozen soils is discontinuous. The thaw settlement is due to the snow accumulation along the road embankment which insulates the ground surface in winter and prevents further ground freezing.