Two ice coring transects in the Shokalsky Strait were made in order to analyze a spatialheterogeneity in the structure of fast ice in the area of the research station “Ice base Cape of Baranov”. The first transect was 16 km long made off the shore of Bolshevik Island in a western direction across the Shokalsky Strait. The second transect was made along the eastern shore of the Shokalsky Strait. Structural analysis of the recovered sea ice cores shows that fast ice in the Shokalsky Strait features a complicated multilayer structure formed of congelation ice, congelation-frazil ice, frazil slush, and infiltration formations. Various conditions of ice formation form the ices of various genetic types. In terms of ice thickness, a sequence of layer occurrence and type, all level fast ice of the Shokalsky Strait in the area of the station can be divided into three main groups. The group I, being the most common one, is the ice group formed directly in the strait, approximately outside the 100 m isobath. Its structure comprises three to four layers. The average ice thickness measured in the end of May was 132 cm. A distinctive feature of the ice belonging to (or associated with) this group is the presence of a distinct lamination in the texture pattern for almost all recovered ice cores. The ice of this group also has an increased salinity compared to the ice of other groups, especially in the upper layers.The ice of the group II prevails, mainly in closed bays or gulfs. This group ice forms in dynamically stable conditions. Formation of fast ice in these regions of the study area began some earlier than in other locations, and the thickness of this ice reached 160 cm or more.The ice of the group III is transitional from the group II to the group I. Its distinctive feature is the presence of a thick layer of rafting ice. The main place of its formation is the boundary of separation of fast ice with drifting ice or open water.In the Shokalsky Strait, in the bays and in the coastal regions, there was observed the spatial ordering of the columnar ice crystals. This feature was especially pronounced in level fast ice from the open part of the strait.

The determination of the main physical properties of the fast ice around the research station "Ice base Cape of Baranov" was carried out from May 23 to August 7, 2014. At the beginning of the observations the ice was a system of three main layers reflecting the conditions of fast ice formation. The top 70 cm of the ice was formed under the conditions of dynamic variability. The ice formation to the level of 110 cm was more stable, and the lowerst layer below 110 cm grew without hummocking and thawing. In the second decade of June the ice accretion began on top due to recrystallization on snow and ice boundary. In the third decade of June the accretion process at the ice-snow interface was replaced by surface melting and destruction layer development. These changes are assumed to begin as maximum air temperatures keep above zero. By the second decade of July all the ice core had undergone serious internal changes. In the third decade of July the process of inter-crystalline-binding degradation affected the whole ice core. Citation: Borodkin V.A., Kovalev S.M., Shushlebin A.I. Change of structure and some physical properties of level fast ice during the spring and summer period of 2014 in the vicinity the research station "Ice base Cape Baranov". Problemy Arktiki i Antarktiki.

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The article presents the results of studies that complement each other. New methods of instrumental studies of the physical and mechanical characteristics of ice and ice cover are considered.There is briefly described the complex system to developed in the AARI (Arctic and Antarctic research Institute) to determine the strength characteristics of ice formations in natural conditions. The results of determining the ice strength in wells (local strength) at the research station of AARI “Ice Base Cape of Baranov” are presented. The coefficient of comparison of local strength and strength of samples under uniaxial compression is obtained. This allows to determine the ice strength without sampling and testing of samples. On a large experimental material, linear and quadratic approximations for local ice strength were obtained. The influence of the indenter penetration rate on the local ice strength is studied.There is considered the application of the contact remote method for monitoring the dynamic state of the ice cover in order to obtain new data for creating a method of predicting the phenomena of compression and destruction of sea ice in real time.To study the large-scale mechanics of ice during dynamic processes in the air — ice — water system, a modular-block system for ice cover monitoring was developed. The layout of the system was tested in Arctic expeditions.The developed complex system for determining the strength characteristics of ice formations in natural conditions and the modular-block system for monitoring the state of the ice cover complement each other, suggest their further development and improvement, provide wide opportunities for ice research.

In last two decade, studies of ice ridge morphometry and strength properties have been actively carried out. Thermal drilling of ice and experiments to determine the local strength of ice using a borehole jack are performed. The paper discusses the issues of joint use of thermal drilling equipment and borehole jack for the ice cover research. Two approaches to the comparison of the results obtained by these two methods are considered. Average penetration rate versus local ice strength dependences are presented. With increasing ice strength and decreasing penetration rate the interval of changes in the ice strength increases and correspondence of the strength to the penetration rate decreases. Based on the results of ice ridges research, depth-wise distributions of local strength and thermal drill penetration rate are compared. Difference between the average thicknesses of the consolidated layer obtained from these distributions was 5 %.