Active Layer Dynamics Near Norilsk, Taimyr Peninsula, Russia

This paper provides information on active layer thickness (ALT) dynamics, or seasonal thawing above permafrost, from a Circumpolar Active Layer Monitoring (CALM) site near the city of Norilsk on the Taimyr Peninsula (north-central Siberia) and the influences of meteorological and landscape properties on these dynamics under a warming climate, from 2005 to 2020. The average ALT in loamy soils at this 1 ha CALM site over the past 16 years was 96 cm, higher than previous studies from 1980s conducted at the same location, which estimated ALT to be 80 cm. Increasing mean annual air temperatures in Norilsk correspond with the average ALT increasing trend of 1 cm/year for the observation period. Active layer development depends on summer thermal and precipitation regimes, time of snowmelt, micro-landscape conditions, the cryogenic structure (ice content) of soils, soil water content leading up to the freezing period, drainage, and other factors. Differences in ALT, within various micro landscape conditions can reach 200% in each of the observation periods.

Engineering surveys of linear communication corridors taking into account geotechnical monitoring of treatment tubes

The necessity of oil and gas fields arrangement in the Extreme North and developing updated edition of rules’ for making engineering surveys codes, taking into account the specific features of the oil and gas fields territories with heaving mounds of permafrost (MMP) is considered in details. The developed models of temperature fields enable predicting possible deformation changes in the geospatial position of the underground and aboveground components of the heaving mounds. It is recommended that the corridor of linear communications be located at least 50 meters from the underground component of the heaving mound and 100 meters from the upper line of the intersection of the heaving mound with the earth’s surface. A new formula for determining the depth of thawing is proposed, taking into account the amount of seasonal thawing and the lateral influence of the heave hill. The research results are introduced in the production of engineering surveys in Samburg, Centillica and Yamburg.

Method of delineation of in the area of Lake Churapcha in Central Yakutia: generalization of engineering and geological surveys of 1995 and study of modern polygonal microrelief

The object of this research is the ice wedge casts and concomitant polygonal microrelief. The subject of this research is the delineation of ice wedge casts on the margin of southern exposure of the Lake Churapcha in Central Yakutia. It is a known fact that in permafrost areas, a pronounced polygonal microrelief is a sign of the presence of ice wedge casts. In geology, “delineation” is the outlining of contours and delimitation of boundaries of the deposits, minerals, and zones with different quality of mineral raw materials and mining-geological conditions, according to the data of geological study for rational development. Ice wedge casts and there is such deposit. The article summarizes the results of field engineering and geological surveys conducted in 1995 on the shore slope of southern exposure the lake that contains ice wedge casts. The author also examines the data from modern satellite images for detecting the activation of polygonal microrelief. The surveys of 1995 confirmed the widespread occurrence of ice wedge casts in the indicated district. According to geological section, the ice wedge casts were identified and delineated. The results of section of the bottom of lake-reservoir demonstrate that it is located in the “thawing bowl”. The presence of ice wedge casts is also indicated by a pronounced polygonal microrelief, which is confirmed by satellite images. As a result of climate warming, the upper limit of ice wedge casts may also change, approximately to 0.3 m, which depends on the air temperature, amount of precipitation and depth of seasonal thawing.

Spatial analysis of permafrost conditions distribution on the Federal highway P504 "Kolyma" (Yakutsky site)

The Yakutsky site of the Federal highway P504 "Kolyma" with a length of 1197 km was investigated. A GIS project was created in ArcGIS format. A spatial geographical analysis of geocryological conditions (soil temperature, seasonal thawing depth, cryogenic processes) using GIS technology was carried out. 12 types of terrain have been identified by cutting out a scale of 1:1 500 000 from the Permafrost-landscape map of the Republic of Sakha (Yakutia). Spatial analysis results are reflected in the form of maps. Quantitative characteristics of permafrost conditions are given in the form of diagrams. It was revealed that the road was mainly laid along sections of low terraces (33,2% of the total area of 100 m of the zone) and the inter-alas type of terrain (10,3%), composed of high-ice deposits. In these areas, frost cracking is most often expressed in combination with other cryogenic processes (53,6%) and thermokarst (21,7%). The temperature of soils in the landscapes of the studied territory most of all varies from −2 to −4 °, the lowest temperatures (−9 °) are found in 3% of the territory in the mountain lichen tundra of the Verkhoyansk Range. The maximum depths of seasonal thawing (> 2,5 m) can be traced only 5% of the total territory. The prevailing value of seasonal thawing depth is from 1,5 to 2 m. Keywords: permafrost conditions, GIS technologies, spatial analysis, soil temperature, permafrost processes, Kolyma highway.

Monitoring of soil temperatur on permafrost in natural and anthropogenic disturbed conditions in the Tunkinskaya Depression

The territory of the study is the Tunkinsky intermountain basin (South-Western Baikal region, Republic of Buryatia) which belongs to the area of sporadic (island) distribution of permafrost. Soil temperature controls many biotic and abiotic processes in it, so it is important to monitor the freezing and thawing regimes in peat and mineral soils. The object of the study is coarse-humic cryogenic soils on sandy lacustrine-alluvial sediments. The first site was represented by natural coarse-humic cryogenic soils under spruce forest, while the second site was organized on the area where in 1960s the forest had been destroyed and the soils were ploughed. At the end of XX century, the arable lands were abandoned, and now they are covered with steppe grasses (the long fallow). Both sites are located on the permafrost. The atmospheric-soil measuring complex was used to study the state of both the perennial and seasonal permafrost at these two sites. The soil temperatures were measured in automatic mode with a time interval of 1 hour from July 1, 2013 to June 30, 2017 along the soil profile from the surface down to a depth of 320 cm. Anthropogenic interference on one of the sites resulted in changes in vegetation cover, the soil moisture as well as the morphological structure and granulometric composition of the upper part of the soil layer. This caused changes in the temperature regime of the permafrost and its degradation with lowering of its upper limit. The soil on the long fallow is better warmed up and cools down faster than it takes place under the spruce forest. As a result of this, the maximum annual temperature on the surface here is higher by 10 °C, while at a depth of 320 cm – by 5 °C, and the minimum annual temperature on the surface is lower by 7 °C, while at a depth of 320 cm – by 1 °C. On the anthropogenically disturbed area, the warm period (at the soil temperature above 0 °C) on the surface is, on the average, by 22 days longer than on the natural lot. These differences are observed at all depths. As a result, the perennial permafrost is retained under the spruce forest below 130 cm throughout the year (soil temperature −0.2 ÷ −0.9 °C), while on the fallow the zero isotherm during seasonal thawing falls much deeper 320 cm, and the soil in the layer of 240–320 cm warms up to 2–5 °C.

About the nature of short-period fluctuations of seasonal thawing depth in tundra soils

The series of 20-year-long observations of seasonal thawing have been studied on CALM plots in Eurasia and North America. The short-term (2-5 years) fluctuations of the active layer are considered. Similarities and differences in seasonal thawing of tundra soils in circumpolar countries are noted. The dynamics of seasonal thawing is analyzed by the example of two CALM plots in the Chukotka Autonomous District. Time series of changes in the depth of seasonal thawing are described using the mathematical methods. The amplitude, frequency and periods of oscillations are determined for them. The comparative graphical and statistical analysis of climate and seasonally thawed layer variations allowed us to judge on the nature and degree of influence of meteorological factors on the depth of soil thawing. The problems of interpretation of intra-century fluctuations of climatic parameters and seasonal thawing are considered. It is concluded that the duration of the warm season affects significantly the depth of seasonal thawing. It is noted that ignoring the intra-century variations in the parameters of climatic and permafrost landscapes is the cause of inconsistency of judgments about climate change trends and forecasts of permafrost degradation. A new concept of “climatic year” was proposed as the conjugation of weather conditions for 2-3 years equally affecting the depth of thawing. The established statistical regularities in changing permafrost-climatic conditions can be used for the preparation of 3-5 and 10-15 summer weather forecasts. The use of the ratio of the average values of the amplitude to the period of short oscillations as an indicator of the stability of the roof of permafrost is justified. The hypothesis of the influence of solar and technogenic electromagnetic radiation in the radio-wave range on the degradation of underground ice of the active layer and Arctic ice is proposed.

The GIS-based approach for the permafrost active layer depth mapping

<p><strong>Abstract.</strong> The depth of the active layer is highly valuable parameter of the biochemical processes and ecosystem dynamics in changing climate. Site area of our investigation was situated in the Evenkiysky District of Krasnoyarsk Krai, Russia near Tura settlement. We used field measurements of seasonal thawing layer depth (active layer depth) to estimate its spatial variability and its dependency of topography-based variables (elevation, slope and aspect). The spatial analysis of field sample plots location and after-forest-fire period length helped us to build the reference table and then extrapolate this data in a form of map for the site area. The produced map of active layer depth and applied data processing scheme are now using for the complex analysis and modelling of hydrochemical processes in terrain- and water-ecosystems.</p>