During the field campaign in August 18–30, 2020 the meteorological regime and heat balance of the glacier surface were investigated in the crater of Mt Elbrus Eastern Summit (5600 m a.s.l.) together with the GPR measurements of the ice thickness and seasonal snow cover. Preliminary data analysis allowed the following features: the predominance of synoptic fluctuations over the diurnal ones; the high values of average and maximum wind speed associated with the impact of jet streams and with influence of leeward storms; extremely high temporal variability of relative humidity and its very high deficit in cloudless conditions conducive to intensive evaporation and sublimation from the snow surface. The maximum thickness of ice in the crater reaches 100 m, and the average is 34 m. A new ice core with a length of 96.01 m from the glacier surface to its bed had been obtained. The drilling speed varied from 11 to 1 m/h, decreasing with depth from 4.5 to 4.0 m/h on average. The thickness of the snow-firn mass is about 20 m, which is three times less than on the Western Plateau of Mt Elbrus. According to measurements in the borehole, temperature at the glacier bed is −0.6 °C. The calculated heat flux is 0.39 W/m2. Air sampling was carried out in the crater of the Eastern Summit of Elbrus and on the Garabashi glacier. Repeated measurements of the soil temperature in the fumarole field on the outer edge of the crater of the Elbrus Eastern Summit allow the conclusion that the temperature regime is stable.

The distribution of cold and temperate ice and water in polythermal glaciers significantly affects their dynamics, thermal and hydrological regime. Radar techniques are an effective remote method of their studies that allows one to determine a glacier thickness by the delay time and to estimate the water content in temperate ice and at bedrock by the intensity of reflections from the interface between cold and temperate ice and the glacier bed. In case study of Austre Gronfjordbreen in Spitsbergen and Central Tuyksu glacier in Tien Shan we consider the features of their hydrothermal structure in spring and summer periods using the data of ground-based radio-­echo sounding at frequency of 20 MHz. To estimate the relative water content, we used data from measurements of relative power reflections from the cold-temperate ice interface, at the bedrock, and from the temperate ice body. In these glaciers (Austre Gronfjordbreen and Central Tuyksu), the average thickness of cold and temperate ice is, respectively, 61 ± 6 and 27 ± 2 m, and 39 ± 4 and 20 ± 2 m, the volume of cold ice is 0.466 ± 0.005 km 3 and 0.044 ± 0.002 km 3 , and volume of temperate ice is 0.104 ± 0.001 and 0.034 ± 0.001 km 3 . Warm ice contains 2080 × 10 3 and 680 × 10 3 m 3 of water, respectively, with an average content of 2%. Measurements along the longitudinal profiles of these glaciers showed that in some parts on Austre Gronfjordbreen in the spring period the average intensity of reflections from the cold­temperate ice interface and the bedrock is −0.02 – −26.3 and −6.0 – −11.8 dB, respectively, and at the whole profile this is −13.36 dB. At Central Tuyuksu glacier the spring values are −14.5 – −32.4 and −29.6 dB, respectively. We attribute such differences of glaciers to the different water content in the temperate ice below and above these boundaries, to the specific distribution of the ice facies zones and glacial nourishment, to the different intensity of surface melting in the spring and summer periods, and to the different crevassing and velocity of glaciers.

No tree-ring chronologies were reported so far in the International Tree Ring Data Bank for the central part of the East-European Plain. This absence is traditionally explained by the lack of motivation for tree-ring research in this area. Indeed, due to the intense anthropogenic press the old trees are rare in this region and the climatic signal embedded in the ring width is not strong and is always complex. In this study we present the new tree-ring network of 9 ring width chronologies of pine ( Pinus sylvestris ) up to 297 years long in a large region of about 450 km in diameter in the Central Russia (54–57N, 33–40E) and analyze their climatic response. Tree ring growth in the region is controlled by both temperature and precipitation of vegetation period, and all the analyzed chronologies have signifi cant correlation with summer PDSI values (with coeffi cients up to r ≤0.4). All of them were sampled after the year 2010 when a severe summer drought spread over the European part ofRussia. This allowed spatial analysis of 2010 year annual ring (and rings related to the years of other known severe droughts of 20th century) in the context of drought impact on tree growth. This study is a starting point for constructing large tree ring network for further investigation of severity and spatial distribution of droughts in European Russia in the past.