As the area of the sea ice cover has considerably reduced in the recent years, the Arctic Ocean surface layer has become more exposed to the effect of atmospheric processes. In order to evaluate the influence of the new conditions on the surface layer state, a large array of winter oceanographic data was used to calculate the Arctic Ocean mixed layer thickness and salinity along with the thickness and salinity of the halocline layer for the 1950-2013 period. Analysis of the interannual variability of the surface layer parameters listed has shown that the mixed layer thickness has increased in recent years, from 30-35 m in 1950-70s to 40-44m in 1980-2000s. The halocline thickness, conversely, has decreased from 65m in 1950-90s to 50 in the 2000s. At the same time, mixed layer salinity and the salinity of the halocline layer has become lower in the 2000s by about 0,5 % compared with 1950-90s. Three periods with distinctive configurations of the fields of the surface layer parameters have been identified. These quasi-20-year periods correspond to different climatic stages with different regimes of the atmospheric circulation. However, this is certainly not the only cause of the changes that occur in the surface layer condition. To reveal other causes of these changes, statistical methods were used to analyze the time series of the Arctic Ocean surface layer parameters. Linear regression equations allowed us to find out that the variability of the mixed layer thickness and salinity is almost equally determined by changes of the atmospheric circulation and fluctuations of the water exchange with the neighboring oceans along with river runoff and ice processes. At the same time, the thickness and salinity of the halocline layer strongly correlate with mixed layer parameters and, as there is no direct contact with the atmosphere, their variability is determined mostly by the mixed layer condition and the underlying Atlantic waters.

The aim of the study was to identify the basic characteristics of ice drift in the south-western Kara Sea and to estimate the extreme drift speed of given probability, including its spatial variability and statistical correlation with the main drift-forming factors.

In order to obtain the ice drift data, the numerical dynamic-thermodynamic model of ice cover evolution developed in AARI was used. Its basic specific feature is imitation of ice cover with the help of so-called markers (conventional ice floes). Using three variants of the model grid net (25, 12.5 and 5 km), the ice conditions in the Baidara Bay and the adjoining area in January-March 2018 were simulated.

The analysis of the simulation results showed that the average ice drift (average ice transport) is directed from the Baidara Bay to the open sea, i.e. northward with slight deviations mostly to the west. A less detailed grid net results in a smoothed ice drift field, while an increase in the spatial resolution of the model increases the spatial contrasts of the ice drift.

The maximum values of the extreme ice drift velocity expressed as “once per N years” occur in the northern part of the model area at the directions of the north-western quarter (up to 1.5-1.8 m/s “once per 10 years” - “once per 100 years”, respectively). The frequency of ice drift velocity exceeding 0.3 m/s is about 4-7 %, and that of ice drift velocity exceeding 0.6 m/s is not more than 1 %.

At low drift velocity, the role of inertia is very high, but as the drift rate grows, the inertia contribution decreases noticeably. At increasing drift velocity, the statistical correlation between the ice drift (on the one hand) and the wind, current and sea level tilt (on the other hand) becomes evident. This effect is especially evident for the correlation “drift / wind”. The correlation “drift / ice pressure” depends on the drift speed more or less noticeably at low and high drift speeds, when unidirectional changes of the ice drift and ice pressure happen more often than the opposite ones. At the drift velocities within 0.15-0.60 m\s, the correlation between the ice drift and ice pressure is insignificant, i.e. the unidirectional and opposite changes of the ice drift and ice pressure are almost equally likely.

The paper is based on the results reported in an invited speaker presentation at the scientific conference dedicated to the 100th anniversary of AARI in March 2020. The features of present-day rapid climate changes in the Arctic and their consequences are assessed. The presented results include those obtained in the framework of the program of the Presidium of the Russian Academy of Sciences "Climate change: causes, risks, consequences, problems of adaptation and regulation" and the Russian-German project QUARCCS (QUAntifying Rapid Climate Change in the Arctic: regional feedbacks and large-scale impacts). An assessment is made of the relative contribution of natural and anthropogenic factors to the formation of temperature trends at different time horizons in the Arctic. In view of the rapid changes of the Arctic climate, the prospects of the Northern Sea route are examined. According to the estimates obtained, the dominant role of radiative forcing is manifested in the Arctic latitudes on time scales of about half a century or more.

New climatic phenomena (in particular, the formation of craters in the Yamal Peninsula under the conditions of melting permafrost) and new effects (including the change in the trends of changes in sea waves in the waters of the Arctic basin) indicate the achievement of a certain critical level of regional and global warming, comparable to the warming of the Holocene Climate Optimum. At the same time, modern climate models can not only reproduce the key features of current climatic regimes and their variability, but also provide adequate predictive estimates even for complex processes in the Arctic.

Situations in which water levels in summer fall below design (critical) marks for at least 10 days are considered dangerous phenomena. In such situations, navigation is hampered or stopped, resulting in significant economic damage. As our previous studies have shown, the mouth areas of the rivers of the Ob-Taz region that are used for navigation are prone to these dangerous phenomena. The aim of this work is to analyze the duration of the water level standing below the design marks and to estimate its characteristics for the navigation period at the posts Salekhard, Aksarka, Nyda, Nadym, Samburg, Sidorovsk, Tasovsky, Nahodka over an extended series of observations. Of the posts listed, the analysis has not previously covered Aksarka and Nadym data. Project levels have changed for some of the posts over the years, requiring updated estimates. The analysis was carried out on the basis of average daily levels at the posts for the period 1936-2013 published in the annual edition of the Water cadastre. If necessary, information on the water flow was included. Unfortunately, the quality of the data for most of the posts except Salekhard is not satisfactory due to numerous passes. The technique consists in the analysis of continuous level standing relative to the design values by specified intervals of duration. The results show that all the posts experienced levels lower than the design marks. In Nahodka it happened annually, in Nadym, Samburg, Sidorovsk — in 75.6 %, 68.3 %, 54.2 % of all the years of observations, respectively. Of all the cases of standing levels below the design mark, those of continuous standing with a dangerous duration were observed in Sidorovsk 71 %, Nadym 67.3 %, Samburg 41.1 %, Nahodka 40.0 %, Aksarka 26.1 %, Nyda 19.1 %, Salekhard 16.7 %. Only in Tasovsky were there no cases of dangerous duration. The largest number of years with dangerous cases fall on the 10-th anniversary of 1981-1990. In individual navigation seasons, two to four cases of continuous standing levels of dangerous duration were observed. At the same time, minimum average daily levels fell below critical values by a value from 189 cm (Nahodka) to 53 cm (Samburg). The maximum number of days with cases of dangerous duration in one season was in shares from the period of open channel from 91.4 % (Nahodka) to 36.6 % (Salekhard). The sum of days with levels below the design values for the season depends inversely on the amount of river flow.

Central Antarctica is characterized by a crucial lack of information on climate variability during the late Holocene. The study of firn cores obtained from the central part of the East Antarctic Ice Sheet is essential for the reconstruction of the paleoclimatic conditions at the continental and regional scales over the past 2,000 years (the Late Holocene). Based on glaciological and isotopic data from the shallow VK16 core drilled in the vicinity of Vostok Station over the periods of the 62th (2016-2017) and 63th (2017-2018) summer seasons of RAE, climatic characteristics have been reconstructed for the period 216 BC - 2010 AD. Studies of the VK16 core were carried out in two stages: firn density and electrical conductivity measurement (ECM), as well as sampling, was performed in the glaciological laboratory of the 5G drilling complex (Vostok Station) soon after the firn recovery, while the isotopic composition of the core samples was measured by a Picarro L-2120i laser analyzer in the Climate and Environmental Research Laboratory of AARI. In the ECM profile of the core, we discovered 14 absolute age markers (layers containing the products of known volcanic eruptions). These markers have allowed us to develop a robust chronostratigraphic scale for this core. We have shown that the main feature of the Late Holocene climate in this part of Antarctica is that the near-surface air temperature remained essentially constant throughout the whole time period under consideration. At the same time, the snow accumulation rate varied significantly around a mean value of 1.83 g cm-2 year-1, while the last 200 years were characterized by the highest snow accumulation rate, equal to 2.08 g cm-2 year-1. In this paper, we describe methods for studying firn cores, which can be useful for further research, and present first preliminary data on the climate variability in the vicinity of Vostok Station during the late Holocene.

The paper presents an approximate solution to the previously unsolved problem of a semi-infinite ice plate bending under the action of concentrated and distributed moments. It is shown that the load from the moment on the ice field occurs when the latter is affected by significant horizontal forces, whose area of application does not encompass the entire thickness of the ice cover. The need to consider this type of horizontal forces has recently arisen in connection with the consideration of a number of applied problems of marine ice engineering. The interaction of ice with vertical shipboards or those inclined at small angles causes ice failure in the immediate vicinity of the boards under the action of horizontal forces. The paper gives an approximate solution to the problem. The results of calculations show that the concentrated moment is not able to break the ice cover near ship sides. At the same time, the moment distributed over some part of the ice edge may induce such failure. The paper obtains theoretical relations to describe this process approximately.

The ice-resistant self-propelled platform (IRSPP) named North Pole that is currently under construction at the JSC Admiralty Shipyards is designed to carry out year-round scientific research in the Arctic Ocean. The IRSPP will be equipped with a unique ice loads monitoring system (ILMS). The technical requirements for the ILMS were developed in the Department of Ship Performance in Ice of the AARI. The ILMS should ensure a safe operation of the IRSPP in ice conditions (operational function) and serve as a measuring tool for researching of the mechanics of deformation and destruction of ice (scientific function). Analysis of ice conditions at different stages of IRSPP operation showed that the main scenario of ice interaction with the IRSPP hull will be the action of ice under compression on the middle part of the hull during drift.

The monitoring of the stress-strain state of the hull is carried out by a complex system of fiber-optic strain sensors placed on different elements of the hull structures. The largest number of sensors are located on the side plating in the middle part of the IRSPP hull. The locations of the sensors were determined by finite element analysis of the stress-strain state of the IRSPP hull under the action of ice load. To monitor the stress-strain state of the surrounding ice field, up to 16 pressure sensors frozen into the ice are provided. Also, the system receives and stores data on the angles of roll, trim, yaw of IRSPP, its longitudinal, lateral and vertical accelerations, and the surrounding hydrometeorological conditions: wind speed and direction, air temperature, atmospheric pressure, and the geographical position of the platform.

ILMS will significantly improve the safety of IRSPP operation during prolonged drift in ice conditions. Besides, the ILMS provides the platform hull with the functions of a measuring tool for studying the mechanics of deformation and destruction of sea ice in interaction with the engineering structures.

The main purpose of this work is to create a comprehensive system for studying the processes of ice impact on structures in order to obtain new data about the parameters and nature of ice loads.

The paper presents results of studying the diagenetic transformation of bottom sediments from two freshwater lakes — Talatinskoe and Tundrovoe — in the Vaigach Island. The study of biogeochemical processes in the conditions of present-day climate instability is especially important for Arctic water ecosystems, since their environmental sustainability is extremely low, and the effects of global warming are most significant. According to available climate forecasts, the Vaigach Island is located in the zone of maximum changes in natural complexes. The lake-river systems of the island are unique island geosystems, but to date they are poorly understood.

Our aim was to carry out comprehensive research on the biogeochemical processes of the sulfur cycle as the geochemical aspect of the bacterial sulfate reduction process, which involves the conjugation of the cycles of carbon, sulfur and iron, participating in redox processes that play an important role in sedimentation and early diagenesis. In order to achieve this goal, a multi-method (hydrochemical, geochemical, etc.) approach was developed using standard generally approved laboratory practices adapted to the study goals.

Based on the pollen data, it was found that the formation of the bottom sediments of Lake Talatinskoe occurred in the current climatic conditions of the tundra. The data on the distribution of grain size fractions allow us to conclude that the sediment sequences of both lakes undergo regular destruction and mixing during seasonal freezing-thawing. This was reflected in the random distribution of all the parameters studied and in the impossibility of determining the sedimentation rate. The data obtained on the quantitative characteristics of sulfate reduction parameters (reduced compounds, forms of reactive iron, the amount of organic matter and its qualitative composition), their distribution and transformation indicate a low intensity of redox processes in precipitation. The most likely reason for this is the high degree of humification of the terrigenous organic matter and the low temperatures of the microorganisms’ habitat.