Seasonal Thaw Depth Research Articles

Spatial Distribution of Thaw Depth in Palsas Estimated From Optical Unoccupied Aerial Systems Data

ABSTRACTMaximum seasonal thaw depth, referred to as active layer thickness (ALT), is one of the key parameters used to monitor permafrost conditions. ALT maps based on interpolation of point measurements or derived from coarse or moderate spatial resolution satellite data often hide small‐scale spatial variations in thaw depth resulting from differences in surface characteristics and microtopography. To model and predict changes in hydrological and biogeochemical processes in permafrost areas accurately, high‐resolution remote sensing‐based estimations of ALT are needed. Therefore, we applied random forest (RF) regression on a set of topographical and spectral vegetation indices derived from optical unoccupied aerial systems data, Landsat 8 land surface temperature (LST) data, and field measurements to estimate thaw depths in palsas at three mires in north‐west Finland. We also analyzed differences in thaw depths between mires located at different elevations, between dome and plateau‐shaped palsas, and between different vegetation and surface cover classes. The RF models resulted in root mean square errors from 2.4 to 5.7 cm between predicted and observed thaw depths and the R2 values of 0.57–0.96. Height from the surrounding fen surface and LST were the most important variables in thaw depth models, although high‐accuracy results were also achieved without LST. The mean thaw depths did not differ between the sites with lowest and highest elevation, whereas the thaw depths were significantly deeper in dome‐shaped palsas compared to plateaus. The thaw depths were significantly different between vegetation cover classes only on plateau‐shaped palsas. The results indicate the high impact of the topography on the palsa thaw depth, thus highlighting the importance of accurate elevation models in spatial modeling of palsa ALT. The methodology presented in this study can be applied to other permafrost regions where field measurements of ALT are accompanied with high‐resolution topographical and multispectral data.

Summer heat wave in 2022 led to rapid warming of permafrost in the central Qinghai-Tibet Plateau

Extreme events with increasing frequency and intensity are significantly affecting the permafrost environment. Analysis using the ERA5-Land reanalysis data revealed that the permafrost region of the central Qinghai-Tibet Plateau (QTP) experienced the summer heat wave in 2022. Four active layer sites experienced maximum active layer thicknesses (ALT) in 2022 (mean: 207.7 cm), which was 20% higher than the mean ALT during 2000–2021 (mean: 175.9 cm). The mean annual ground temperature (MAGT) observed in 2022 was also the highest, exceeding the average of the previous years by 10%. The contribution fraction of heat wave to the seasonal thaw depth of active layer was quantified using Stefan model with ranging from 6.6% to 13.6%, and the maximum contribution fraction occurs in 2022. These findings are helpful to better understand the impact processes of extreme events on the active layer and permafrost.

The Impact of Catastrophic Forest Fires of 2021 on the Light Soils in Central Yakutia

This paper presents the results of studying changes in the main parameters and properties of soils in larch and pine forests growing on sandy soils of the Lena-Vilyui interfluve of Central Yakutia, where catastrophic forest fires occurred in 2021. According to the remote monitoring information system of Rosleskhoz, in 2021, almost 8.5 million hectares of forests burned in Yakutia, which is considered as one of the largest forest fires in Russia and in the world in that year. After the fire passes through the forest floor, the content of organic matter decreases as a result of combustion processes. The acidity of the soil changes towards its alkalization due to the entry of combustion products. Changes in soil profiles occur; turbation processes begin more intensively, which in turn change the natural distribution of soil indicator values such as the organic carbon content, the pH, and the number of exchangeable bases. Due to the sharp increase in heat supply after a fire, the depth of seasonal thawing in the soils of burnt larch forests increases by a quarter and by twofold in pine forests. With the beginning of the thawing of the seasonally frozen layer, all the soils experience waterlogging, and ground water occurs above the permafrost.

Geocryological Conditions of Small Mountain Catchment in the Upper Kolyma Highland (Northeastern Asia)

This research presents a comprehensive environmental assessment of a small mountain permafrost catchment of the Anmangynda River in the Upper Kolyma Highland (Northeastern Asia) over the period of 2021–2023. The study reveals significant diversity in climatic, geocryological, and hydrogeological conditions within this confined area, emphasizing the need for extensive field data collection and monitoring in vast permafrost regions with limited data availability. Key findings include variations in ground temperature, maximum seasonal thaw depth, and depths of zero annual amplitudes of ground temperature at different elevations and landscape types. Groundwater and surface flow dynamics within spring aufeis basins exhibit complex geocryological regimes influenced by icing processes. The presence of aufeis and its impact on local hydrology highlight the ecological significance of this phenomenon. Future research should focus on long-term trends in permafrost dynamics and their relationship with climate change, as well as the ecological effects of aufeis formation on local ecosystems. The study underscores the importance of a multi-faceted approach to environmental assessment, incorporating various environmental parameters and processes, to gain a comprehensive understanding of the intricate interactions within the cryosphere and their responses to changing climate conditions. Such knowledge is essential for addressing broader questions related to climate change, ecosystem resilience, and sustainable resource management in Northeastern Siberia.

Geographical and genetic features of soil formation and diversity of the permafrost soils of Central Yakutia

The aim of the study. The aim of this article was to identify the geographical and genetic features of soil formation in the cryolithozone of Central Yakutia and to assess the diversity of all types of permafrost soils of this territory. Location and time of the study. Soil-geographical and soil-genetic studies were carried out near the Middle Lena, on the territory of Central Yakutia within various geomorphological tiers of the Central Yakut Plain at different times, starting from the 1990s. Methodology. In carrying out these works, widely used methods of soil research were used, such as comparative geographical, profile genetic and comparative analytical in combination with well-known and commonly used analytical methods. At the same time, all the main results of soil studies conducted on this territory by our predecessor permafrost soil scientists were taken into account in a comparative aspect. Main results. According to the obtained results, it is necessary to state that this region of the cryolithozone is characterized by extremely peculiar landscape and climatic conditions of soil formation, the formation of the cryogenic soils occurring in a cryoarid climate, mainly on loose alluvial deposits of various ages, under forest and meadow-steppe vegetation and continuous permafrost. In the studied territory, the cryogenic soil-forming processes are crucial for the development of properties, composition and regimes of these permafrost soils, causing their high diversity and diversity of the soil cover of Central Yakutia. The systematic list of permafrost soils of the studied territory includes 17 types and 21 subtypes of soils and is forecasted to expand as the study of the soil cover of this unique region of the cryolithozone deepens. At the same time, the diversity of soils there is formed by the six types of zonal and azonal forest, five types of meadow-steppe and five intrazonal types of the permafrost soils. A broader concept of "permafrost soils" is proposed, in contrast to that interpreted in the current classification of soils of Russia and WRB, the essence of which is that regardless of the depth of seasonal thawing, all soils underlain by the permafrost are called permafrost soils. In these soils, the interlocking of seasonally and permanently frozen layers is observed in winter. These soils may differ in pronounced cryomorphic features (cryozems, fawn) or not have them (podburs, podzols, chernozems), being characterized by a permafrost type of temperature regime. Conclusion. In the cryolithozone environment of Central Yakutia, elementary soil-forming processes occur under cryogenesis conditions, which in the general hierarchy of soil-forming factors is considered at the subfactorial level; minor variations of the soil-forming factors can change the directions and rates of the soil-forming processes and, ultimately, lead to a high degree of diversity and contrast in the soil cover of the studied territory.

A Conceptual Model to Quantify the Water Balance Components of a Watershed in a Continuous Permafrost Region

In regions characterized by continuous permafrost, hydrological modeling remains a complex activity, primarily due to constraints related to the prevailing climatic conditions and the specific behavior of the active layer. High-latitude regions receive less solar radiation; thus, most creeks are active only during summertime and stay frozen in the winter. To realistically simulate watersheds underlain by continuous permafrost, the heat transfer through the soil needs to be accounted for in the modeling process. In this study, a watershed located in a continuous permafrost zone in Russia is investigated. A model is proposed to integrate this heat transfer into an existing conceptual rain-flow transformation model, Hydrologiska Byråns Vattenbalansavdelning (HBV), to calculate the seasonal thaw depth and determine the components of water balance. The proposed integration is a novelty compared to the standard model, as it enables the physical and thermal properties of the soil to be taken into account. It was found that the proposed model, HBV-Heat, performs better than the stand-alone HBV model. Specifically, the average Nash–Sutcliffe efficiency (NSE) increases by 30% for the whole calibration period. In terms of the water balance components, the results are consistent with previous studies, showing that surface runoff represents 64% of the observed precipitation.

Soil temperature regimes on the southern border of the zone of frozen bogs in Western Siberia

Numto Nature Park (Western Siberia) is one of the southernmost locations of frozen peatlands. In 2019–2022, soil temperatures were measured there using an automatic monitoring system. The measurements were carried out for Murshik Hemic Cryic Histosol on flat palsa peatlands and frost mounds. The temperature for Folic Albic Podzol was measured for reference. The average annual temperature of the soil surface was found to be positive in all study areas: + 0.8 °C on the frost mound; +1.3 °C on the flat palsa peatlands; and + 4.5 °C in Folic Albic Podzol. The low temperature on the frost mound is due to the low snow cover, so the soil surface cools down to the minimum in winter. As for flat palsa peatlands, peat remains frozen all year round, starting from a depth of 0.5 m. On the frost mound, at the same time, the depth of seasonal thawing is 2 m. In winter, the frost penetration on the mound doesn't reach the permafrost table, revealing its probable degradation in case of further climate warming. According to the soil thermal regime classification, the soil on the frost mound falls into the category of long-term seasonally frozen soils, while high palsa peatlands nearby Nadym Town belong to the permafrost type. Data from the nearby meteorological station show a trend of rising air temperature and rainfall. An analysis of the soil temperature regime and the course of exogenous processes demonstrate that Murshik Hemic Cryic Histosol on high palsa peatlands is unstable. Permafrost persists there due to the low thickness of the snow cover on the peaks, which facilitates winter cooling. If the snow-cover height increases, permafrost is likely to melt there.

On aquatic macrophytes in the ultracontinental climate conditions of the Upper Indigirka River

The first results of the study of aquatic macrophytes of the Upper Indigirka River area are presented. The species composition includes ~84 species (~74 vascular plants and more than 10 cryptogamous macrophytes). 47 water bodies of different age, size and origin (tectonic, glacial, river, thermokarst and artificial) were studied. For each type of water bodies, the main ecological characteristics, features of the species composition and vegetation cover are given. The most common type of water bodies of the territory is thermokarst, and the greatest floristic diversity (54 species of macrophytes) is found here. There are 40 species in tectonic lakes, 37 - in rivers lakes, 35 - in glacial lakes, the lowest diversity was for small artificial waterbodies. For the Oimyakon District, new records of protected species are reported: macroalga Tolypella canadensis, vascular plants Isoetes echinospora, Nuphar pumila, Nymphaea tetragona (common and its rare pink-flowered form) and Subularia aquatica. Possible consequences for aquatic ecosystems while maintaining current trends in climate change (increase in average annual temperature, shift to earlier periods of spring warmth, changes in the amount and distribution of precipitation, depth of seasonal thawing of soils) leading to degradation of permafrost and their impact on the biodiversity of aquatic macrophytes in the region are discussed. The most vulnerable aquatic ecosystems of the Oimyakon Highlands are the mature thermokarst lakes.

Влияние температуры на глубину оттаивания дорожного основания

The paper is aimed at a quantitative assessment of the air temperature influence degree on the depth of seasonal thawing of the road soil bases in the permafrost zone. The authors propose a simple algorithm for assessing the influence of the main initial values and the accuracy of their determination on the final result of calculating the depth of soil thawing. They have established that for each value of the average air temperature there is a specific value of the required accuracy of setting it when charring out thermal calculations, which will avoid errors in determining the depth of soil thawing that is greater than what is permissible in engineering practice.

How does humidity data impact land surface modeling of hydrothermal regimes at a permafrost site in Utqiaġvik, Alaska?

Humidity is a basic and crucial meteorological indicator commonly measured in several forms, including specific humidity, relative humidity, and absolute humidity. These different forms can be inter-derived based on the saturation vapor pressure (SVP). In past decades, dozens of formulae have been developed to calculate the SVP with respect to, and in equilibrium with, liquid water and solid ice surfaces, but many prior studies use a single function for all temperature ranges, without considering the distinction between over the liquid water and ice surfaces. These different approaches can result in humidity estimates that may impact our understanding of surface-subsurface thermal-hydrological dynamics in cold regions. In this study, we compared the relative humidity (RH) downloaded and calculated from four data sources in Alaska based on five commonly used SVP formulas. These RHs, along with other meteorological indicators, were then used to drive physics-rich land surface models at a permafrost-affected site. We found that higher values of RH (up to 40 %) were obtained if the SVP was calculated with the over-ice formulation when air temperatures were below freezing, which could lead to a 30 % maximum difference in snow depths. The choice of whether to separately calculate the SVP over an ice surface in winter also produced a significant range (up to 0.2 m) in simulated annual maximum thaw depths. The sensitivity of seasonal thaw depth to the formulation of SVP increases with the rainfall rate and the height of above-ground ponded water, while it diminishes with warmer air temperatures. These results show that RH variations based on the calculation of SVP with or without over-ice calculation meaningfully impact physically-based predictions of snow depth, sublimation, soil temperature, and active layer thickness. Under particular conditions, when severe flooding (inundation) and cool air temperatures are present, care should be taken to evaluate how humidity data is estimated for land surface and earth system modeling.

Long-term variability of the thermal state in the upper horizons of the cryolithozone in Central Yakutia

The results of the 42-year monitoring of the thermal state of permafrost landscapes in modern climate warming conditions at the “Chabyda” observation station (Central Yakutia) are presented. We studied the evolution of the variability of soil thermal state parameters: the temperature of soils on the sole of the seasonally shallow layer and in the layer of annual heat rotations, and the depth of seasonal thawing. The long-term variability of the average annual soil temperature, experiencing significant interannual and short-term fluctuations, has a multidirectional trend, with warming dominating. The main factors regulating the thermal state of permafrost landscapes are the short-period fluctuations in the snow accumulation regime. Despite significant interannual fluctuations, the depth of seasonal thawing responded to climate warming with multidirectional trends, and its increase or decrease was statistically insignificant. We performed a statistical analysis of the observation time series revealing correlations between climate elements (air temperature, total precipitation, average winter snow depth, duration of winter and summer seasons) and relationships between soil temperature regime parameters (Тξ, Т0, ξ) with climate elements. The results of these studies on the thermal state of soils can be applied to homogeneous landscapes in this region. They can also be used to model heat transfer processes in natural landscapes and develop hybrid intelligence methods for diagnosing the state of infrastructure facilities in the Far North based on high-performance computing systems.

Carbon Dioxide Emission from Soils of the Ecotone Zone in the North of Western Siberia

The study area in the north of Western Siberia is located in the southern tundra–taiga ecotone near the southern boundary of discontinuous permafrost zone. Three contrasting ecosystems—pine forests with Albic Podzols; palsa with Histic Oxyaquic Turbic Cryosols, and bogs with Fibric Histosols—predominate in this area. The objectives of the study included evaluation of the CO2 emission from soils in the growing seasons of 2019–2022 and analysis of the factors controlling spatial and interannual variability of the emission. The study included analysis of the soil respiration (static closed chamber method) data and soil hydrothermal parameters in August for four years. In the absence of definite trends in climatic parameters over the past 10 years, a gradual increase in the soil temperature in all ecosystems and an increase in the depth of summer thawing in palsa were observed. These changes were not accompanied by significant changes in the CO2 emission. Its averaged values varied from 485 to 540 mg CO2/(m2 h) in forest ecosystems and from 150 to 255 mg CO2/(m2 h) in the palsa–bog complex with high coefficients of spatial variability. High CO2 emission in forest ecosystems is determined by a favorable hydrothermal regime, high root biomass, and good water-physical properties. Part of the CO2 produced by palsa soils is transported with suprapermafrost water flows toward the adjacent bog and is released from the surface of bog soils. Soil temperature interrelated with seasonal thawing depth proved to be a significant predictor of the spatial variability of CO2 emission from the soils of the palsa–bog complex.

Localized Vegetation, Soil Moisture, and Ice Content Offset Permafrost Degradation under Climate Warming

Rapid Arctic warming is expected to result in widespread permafrost degradation. However, observations show that site-specific conditions (vegetation and soils) may offset the reaction of permafrost to climate change. This paper summarizes 43 years of interannual seasonal thaw observations from tundra landscapes surrounding the Marre-Sale on the west coast of the Yamal Peninsula, northwest Siberia. This robust dataset includes landscape-specific climate, active layer thickness, soil moisture, and vegetation observations at multiple scales. Long-term trends from these hierarchically scaled observations indicate that drained landscapes exhibit the most pronounced responses to changing climatic conditions, while moist and wet tundra landscapes exhibit decreasing active layer thickness, and river floodplain landscapes do not show changes in the active layer. The slow increase in seasonal thaw depth despite significant warming observed over the last four decades on the Yamal Peninsula can be explained by thickening moss covers and ground surface subsidence as the transient layer (ice-rich upper permafrost soil horizon) thaws and compacts. The uneven proliferation of specific vegetation communities, primarily mosses, is significantly contributing to spatial variability observed in active layer dynamics. Based on these findings, we recommend that regional permafrost assessments employ a mean landscape-scale active layer thickness that weights the proportions of different landscape types.

Soils of the Krestovsky and Chetyryokhstolbovoy islands in the National Nature Reserve “Bear Islands” (East Siberian Sea)

This paper presents an investigation of previously unstudied soils of the Arctic islands (Krestovsky and Chetyryokhstolbovoy), which gained the status of a new protected area “Bear Islands” (70°37′–70°60′ N, 160°23′–162°33′ E). Their soils were formed mainly under permafrost conditions (approximately 1 m), with a seasonal thawing depth of 0.3–0.6 cm. The territory of Krestovsky Island is a combination of several landscapes characterized by various types of permafrost soils. Primitive gravelly soils (A–BC(C)) are exposed in mountainous areas. Permafrost tundra low-gley soils (OT–Bg–BCg(C)) are formed on the gentle long slopes under hummocky moss-herbaceous tundra. In natural depressions on cryogenic forms of surface, the soil cover represents a combination of permafrost arctotundra gleyic (O–B–Bg(BC)┴) and humus-gley soils (O–AH–AB–BG┴). Marsh soils (Ad–C(AC)–C′) occur along the low flooded gently sloping coasts of the island. All soils are acidic. Zonal types are characterized by gleying, which brings them closer to the soils of the mainland. The soil cover of Chetyryokhstolbovoy Island, with the most fully developed shrublichen-moss or forb-moss soils, is rather monotonous. Namely it is represented by arctotundra gleyic soils with a profile of the same type in terms of morphological features and physicochemical properties (О–Аd–АВ(g)–Вg(BCg)). The main features of this soil type include the thinness of the surface organogenic horizon, good decomposition of organic matter, high and medium content of humus in the soddy-humus horizon, the absence of surface gleying or its weak severity due to drying out in summer.

Permafrost degradation induced by warm-oil pipelines and analytical results of thermosyphon-based thawing mitigation

The China–Russia Crude Oil Pipeline (CRCOP) has been in operation for more than ten years, and its oil temperature has been increasing annually. Problems with ground surface subsidence and pipeline settlement were found in geological investigations along the CRCOP, indicating the risk of pipeline instability. In this study, a system was established to monitor pipeline–permafrost interactions along the CRCOP. It was found that the seasonal thawing depth (STD) of a borehole 2 m away from the horizontal line of the CRCOP reached about 11 m in 2022. Based on the on-site measured boundary, a laboratory experiment was conducted to study the evolution of the thermal regime, and to investigate the cooling effect of thermosyphons. The results indicated the consistent existence of a thaw bulb surrounding the pipeline, which was open in warm seasons but remained closed in cold seasons and expanded in three directions at different speeds. Thermosyphoning erased the thaw bulb and altered the thermal evolution of the permafrost, with a gradually decreasing STD. The results of this research can serve as a reference for thermal regime assessments of the CRCOP and thaw settlement mitigation along the CRCOP, as well as for other counterparts across the world.

Road foundation thawing at change in Ice content along the active layer depth

The seasonal temperature and humidity regime of the road foundation in the active layer of soil largely determines the reliability and safety of the automobile road use. The aim of this article is a quantitative assessment of the influence of variation in ice content in the active layer of the road foundation soil in the permafrost area on the depth of seasonal soil thawing. Analytical solutions of one-phase flat Stefan problem at varying ice content along the coordinate were obtained. The solution is in the dimensionless form as a Fourier function based on Stefan number and dimensionless simplexes. The dependence of ice content change on the distance was assumed to be linear. Calculations using the obtained formulas were conducted, comparing against formulas assuming that ice content is a constant. It was determined at which ice content gradient averaging the ice content does not lead to an error greater than permitted in engineering practice in determination of the thawing depth. The results of variant calculations are presented as 2D and 3D charts to assess the influence of the initial ice content in the soil and the degree of its variation over the period of road use on the thawing depth of road foundation.

Problems of engineering geomorphology in the settlement zone of the Eg River valley: A case study of Aufeis in Erdenebulgan Soum, Khuvsgul Province, Mongolia

Aufeis formation in the winter season in settlements located in continuous, discontinuous, and isolated permafrost regions of Mongolia has become one of the urgent problems that must be solved in the settlement areas. In this study, the reasons for the formation of Aufeis in the settlement area of Erdenebulgan Soum, Khuvsgul Province, located in the Eg River valley, were clarified. In addition to the analysis of geomorphology and permafrost survey materials, the research was based on satellite image data and calculated using the methods of normalized snow index (NDSI) and snow water index (SWI). In the Eg River valley, the normative depth of seasonal freezing and thawing of subsoil ranges from 2.2-3.7 meters. Depending on the freezing of the winter season, there were long, short, and straight rows of cracks and fractures in the vicinity of river diversions, floodplains, terraces, or along the settlement zone. Over the past 10 years, the average size of the Aufeis area was 5555.8 m², and the average Aufeis volume was 5000.2 m³. In 2022, the Aufeis area increased sharply to 6,381.3 m², which can be related to that year's precipitation and soil temperature fluctuations. According to the area and volume classification of Aufeis in Mongolia, the research area belongs to the III class of medium-sized category, but it is exposed to the space of Aufeis distribution due to the improper expansion of the settlement area and wrong planning. According to the changes in the satellite map over the last 30 years, the diversion of the Eg River has caused the spatial distribution of the Aufeis to move towards the settlement area. This study is important for the planning of the spatial location of towns to determine the methods of pre-research and prevention of permafrost-related phenomena and engineering geomorphological problems.

Interannual and seasonal variations of permafrost thaw depth on the Qinghai-Tibetan Plateau: A comparative study using long short-term memory, convolutional neural networks, and random forest.

An accurate estimation of thaw depth is critical to understanding permafrost changes due to climate warming on the Qinghai-Tibetan Plateau (QTP). However, previous studies mainly focused on the interannual changes of active layer thickness (ALT) across the QTP, and little is known about the changes in the seasonal thaw depth. Machine learning (ML) is a critical tool to accurately estimate the ALT of permafrost, but a direct comparison of ML with deep learning (DL) in ALT projection regarding the model performance is still lacking. Here, ML, namely random forest (RF), and DL algorithms like convolutional neural networks (CNN) and long short-term memory (LSTM) neural networks were compared to estimate the interannual changes of ALT and seasonal thaw depth on the QTP. Meteorological series, in-situ collected ALT observations, and geospatial information were used as predictors. The results show that both ML and DL methods are capable of estimating ALT and seasonal thaw depth in permafrost areas. The CNN and LSTM models developed using longer lagging times exhibit better performance in thaw depth prediction while the RF models are either mediocre or sometimes even worse as the lagging time increases. The results show that the ALT from 2003 to 2011 on the QTP exhibits an increasing trend, especially in the northern region. In addition, 68.8%, 88.7%, 52.5%, and 47.5% of the permafrost regions on the QTP have deepened seasonal thaw depth in spring, summer, autumn, and winter, respectively. The correlation between air temperature and permafrost thaw depth ranges from 0.65 to 1 with the time lag ranging from 1 to 32 days. This study shows that ML and DL can be effectively used in retrieving ALT and seasonal thaw depth of permafrost, and could present an efficient way to figure out the interannual and seasonal variations of permafrost conditions under climate warming.

Spatial and Temporal Variability of Permafrost in the Western Part of the Russian Arctic

Climate warming in the Russian Arctic over the past 40 years shows a variety of patterns at different locations and time periods. In the second half of the 20th century, the maximum rates of warming were characteristic of the subarctic permafrost regions of Russia. But in the 21st century, the locations of the greatest rates of climate warming moved to the Arctic zone of Russia. It was one of the reasons for a sharp increase in permafrost temperatures, an increase in the depth of seasonal thaw, and the formation of closed taliks. It was found that as a result of climate change, the differences in permafrost temperatures between different cryogenic landscapes in the area of continuous and discontinuous permafrost distribution have decreased, and in the area of sporadic permafrost distribution are now practically absent. The thermal regime of the ground shows dramatic changes everywhere with a pronounced reduction in the depth of zero annual amplitude.

Antropogenic Impacts on the Thermal Condition of Permafrost in Central Yakutia

The results of long-term geothermal investigations in disturbed landscapes along the railway, water line and gas pipeline are presented. Human-induced changes in the ground thermal state are analyzed. The study has shown significant increases in mean annual temperature of the upper permafrost layers, as well as in seasonal thaw depth in the inter-alas type of terrain after the removal of trees, ground surface stripping and post-fire clearing. Quantitative estimates are given for the dynamics of mean annual ground temperatures on cuts and burns in relation to vegetation succession.