The research station "Vaskiny Dachi", Central Yamal, West Siberia, Russia – a review of 25 years of permafrost studies

The research station "Vaskiny Dachi" on the Yamal Peninsula was established in 1988. Activities aimed at monitoring of permafrost and related environmental features under a relatively low level of nature disturbances caused by gas field development. Cryogenic processes that may affect the environment and their structures have been of primary interest. Landslides are the most common cryogenic processes in Central Yamal in general and also in the proximity of the station. Field surveys of numerous landslides, analysis of their dependence on climatic parameters and their fluctuations resulted in novel classification of cryogenic landslides based on mechanisms of their development. Dating by radiocarbon and dendrochronology allows the separation of cycles of landslide activation. Cryogenic landslides control the development of other processes, such as thermal erosion, river channel erosion and thermokarst. It also affects topography, vegetation pattern, geochemistry of vegetation, ground water and soils. As a result, permafrost parameters, specifically active layer depth and ground temperature, moisture and ice content in the active layer, depend indirectly on landsliding. Monitoring within the framework of the main programs of the International Permafrost Association, such as Circumarctic Active Layer Monitoring (CALM, since 1993) and Thermal State of Permafrost (TSP, since 2011), play an important role among the research activities. From the collected data one can conclude that ground temperature increased on average by about 1 °C since the 1990s. At the same time, active layer fluctuations do not exactly follow the air temperature changes. Spatial changes in ground temperature are controlled by the redistribution of snow which is resulting from strong winds characteristic for tundra environments and the highly dissected relief of Central Yamal. Temporal variations rather depend on air temperature fluctuations but the rate differs in various landscape (environmental) units. While the spatial distribution of active layer depth depends on lithology and surface covers, temporal fluctuations are controlled by ground temperature, summer air temperature, summer precipitation, and in general may contravene climate warming due to specific combination of all factors

GIS and field data-based modelling of snow water equivalent in shrub tundra

An approach for snow water equivalent (SWE) modelling in tundra environments has been developed for the test area on the Yamal peninsula. Detailed mapping of snow cover is very important for tundra areas under continuous permafrost conditions, because the snow cover affects the active layer thickness (ALT) and the ground temperature, acting as a heat-insulating agent. The information concerning snow cover with specific regime of accumulation can support studies of ground temperature distribution and other permafrost related aspects. Special attention has been given to the presence of shrubs and microtopography, specifically ravines in a modelling approach. The methodology is based on statistical analysis of snow survey data and on GIS- (Geographical Information System) analysis of a range of parameters: topography, wind, and shrub vegetation. The topography significantly controls snow cover redistribution. This influence can be expressed as increase of snow depth on concave and decrease on convex surfaces. Specifically, snow depth was related to curvature in the study area with a correlation of R=0.83. An index is used to distinguish windward and leeward slopes in order to explain wind redistribution of snow. It is calculated from aspect data retrieved from a digital elevation model (obtained by field survey). It can be shown that shrub vegetation can serve as a ‘trap’ for wind-blown snow but is not a limiting factor for maximum snow depth, since the snow depth can be higher or lower than shrub height dependent on other factors