FEATURES OF THE SNOW COVER FORMATION IN SIBERIA AND THE RELATIONSHIP WITH THE ATMOSPHERICS DYNAMICS ANOMALIES IN THE NORTHERN HEMISPHERE

Variation of the snow cover extent and the dates of the beginning and end of its formation in Western Siberia (WS) for the fall-winter season was analyzed. We used the NOAA satellite data on the snow cover extent in Northern Hemisphere and data from meteorological stations from the RIHMI-WDC dataset. An increase of the interannual variation of the dates of the beginning and end of the snow cover formation was obtained. For the northern WS territories and territories located on significant heights, a later onset of snow cover is shown in the NOAA data compared to stations observations. Using the ERAInterim reanalysis and NOAA data, we also analyzed the features of the atmospheric modes of variability and wave activity, which are manifested for the anomalously rapid snow cover formation in the WS. The results obtained indicate the insignificance of the influence of the anomalies in the rate of the WS snow cover extent increase. We also suggest that the snow cover formation anomalies are a consequence of the atmospheric state anomalies on a hemispheric scale.

Features of Fauna and Ecology of Ixodid Ticks Parasitizing in the Central Part of the East European Plain

The purpose of the research is finding out features of fauna and ecology of ixodid ticks parasitizing in the Non-Black Earth Region of the central part of the East European Plain, which inhabit the Kaluga Region. Materials and methods. Ixodid ticks were collected and recorded according to generally accepted methods in all districts of the Kaluga Region and the city of Kaluga in 2009–2019 during their activity (in the spring from the melting of snow and until late autumn before the snow cover formation). A total of 11,282 ticks were collected in 412 flag-hours, of which 7,421 (65.7%) were collected from vegetation and 3,861 (34.3%) from animals. We studied open meadow and field areas, forest and shrub areas, closed meadow and field areas, and wetland stations and settlements. The species was identified using the Atlas of ixodid ticks by Ganiev and Aliverdiev (1968) and the Atlas by Shevkoplyas (2008). Results and discussion. There are two species of ixodid ticks in the Kaluga Region, Ixodes ricinus and Dermacentоr reticulatus. The number of D. reticulatus slightly exceeds (by 6%) I. ricinus, 53 and 46% respectively, which is explained by the even distribution of forest and meadow (pasture) biotopes in the Region. The abundance index of I. ricinus was 16.8±1.32 individuals per 1 flag-hour in forest biotopes, and 11.6±1.12 individuals per 1 flag-hour in meadow biotopes. The abundance index of D. reticulatus was 10.8±1.14 individuals per 1 flag-hour in forest biotopes, and 15.9±1.30 individuals per 1 flag-hour in meadow biotopes.

Interseasonal impact of Siberian snow cover formation rate on the baroclinicity and wave activity over Northern Eurasia

<p>Climate changes can cause a change of pattern of the atmospheric interaction between polar and middle latitudes, which can cause a change in the cyclone formation regime, which in turn can provoke extreme and hazardous phenomena intensification. Therefore, it is essential to understand the nature of the atmospheric interaction in question clearly.</p><p>Due to climatic features, it is precisely in the Siberian part of Eurasia that the most extensive snow cover forms, causing significant radiation cooling in this territory. The snow cover area, and consequently the intensity of radiation cooling, can vary significantly from year to year. It can make a significant impact on the interaction of the troposphere and lower stratosphere of middle and Arctic latitudes not only during the establishment of snow cover but also in the following winter season. Knowledge of the features and patterns of the manifestation of the influence of local disturbances (arising on the surface in the autumn due to the formation of autumn snow cover) on the atmospheric conditions of the following winter can be used as additional information when making seasonal weather forecasts.</p><p>The present study aims to assess the response of the troposphere and lower stratosphere over Northern Eurasia during the autumn-winter period to a rate of the snow cover formation in Siberia.</p><p>We separated the years with the sharp intensive and smooth slow snow cover formation. We analyzed for them the baroclinicity index and its components (the zonal and meridional potential temperature gradient and the Brent-Väisälä frequency) for various isobaric levels (up to 200 hPa), and Eliassen-Palm flux. The results obtained suggest that anomalies in the snow cover formation rate in Siberia can contribute and cause anomalies in atmospheric circulation in the autumn-winter period. However, there is no complete clarity regarding the mechanism of distribution of this influence.</p><p>This work was supported by the Russian Science Foundation grant No. 19-17-00248.</p>

Simulating of snow cover formation by the model of interaction between the land surface and the atmosphere (SWAP)

In framework of the project «The Earth system Models – Snow Models Intercomparison Project» (ESMSnowMIP), calculations of snow storages were carried out on ten experimental sites organized for longterm monitoring of the snow cover variability in various regions of the globe. The calculation method is based on the physical and mathematical description of heat and moisture exchange processes occurring within the system «ground water – soil – vegetation cover/snow cover – surface layer of the atmosphere», and it is implemented in the form of the model of interaction between the land surface and the atmosphere (SWAP). The model was developed at the Institute of water problems (IWP) of Russian Academy of Sciences. The model makes possible to calculate components of water and heat balances and different characteristics of the hydrological regime of terrestrial ecosystems and river basins having different spatial scales and located in different natural conditions. Good quality of reproduction of the snow storages variability on all considered sites is reached that allows consideration of the SWAP model as one of the best models of the snow cover formation. Thus, the SWAP model has a sufficiently optimal degree of complexity of the algorithm for reproducing the dynamics of snow cover, which is necessary and sufficient in global and regional hydrological models describing formation of the water balance of the land in the cold regions of the planet, and can be used to create scenario forecasts of snow dynamics (as the important part of the cryosphere). This conclusion is verified by the results of using the SWAP model to reproduce long-term variability of snow storages in basins of the River Lena and the River Ob (with its tributary Irtysh) which are the two largest rivers of the Russian Federation. The calculated and measured characteristics of snow cover dynamics for these basins are shown to be in good agreement.