New estimates are suggested of harmonic constants of the tide for the summer (August) and winter (April) periods at the Sabetta, Utrenny posts, at the Tadibeyakha and Seyakha posts, as well as at the points of Cape Kharse, Cape Yaptik-Sale, Cape Kotelnikova and Cape Hampul-Yakha. The harmonic analysis of the tide was carried out using the least squares method according to the AARI version. According to AARI expedition observations in Sabetta for the period 2012–2016, and in Salman for the period 2016–2019, average vector estimates for each month of the year have been obtained. The observations were made using the ADCP device installed at autonomous buoy stations. Hourly level observations at the Seyakha and Tadibeyakha posts for the entire observation period from 1968 to 1992 were brought to a homogeneous form using the calibration method. The historical observations of the level at the points of Cape Kharse, Cape Yaptik-Sale, Cape Kotelnikova and Cape Khampul-Yakha, carried out in different years, are of scientific interest. Since the results of their processing and analysis in the original sources contained errors and did not include shallow water constituents, our analysis results are presented. Our tests show a significant contribution of shallow water constituents in the Ob’ Bay to the description of the tide curve and the calculation of the heights and times of high and low waters. Inter-annual and intra-annual estimation is given of the dispersions of the total and tidal level fluctuations in Seyakha and Tadibeyakha for the entire observation period. Comparison of the average seasonal course of the tide in the annual cycle based on the results of tide analysis in Seyakha and Tadibeyakha (XX century) and Sabetta and Utrenny (XXI century) shows significant differences. The study of surges of level is based on uniform series, as well as residual ones (observations minus predictions). 

The present study deals with assessing the impact of the factors that define the interannual variations of ice area of different age categories in the Barents Sea. For the analysis, a set of hydrometeorological and ice parameters was created, potentially influencing the age composition of the sea ice cover. Among these are the climate indices of the Arctic Oscillation, the Arctic Dipole, the Pacific-North American Oscillation, the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation, as well as the surface air temperature, the ice cover in the previous months and the ice outflow on the sea ice in the Barents Sea. Based on the parameters above, statistical equations with high quality indicators have been obtained.

The statistical equations are presented for the period of maximum ice cover in April. The results are provided for three homogeneous sub-areas of the Barents Sea: western, northeastern and southeastern. It is found that the atmospheric circulation pattern is the driver of the interannual variations in the Barents Sea ice age composition. The ice amount of different age categories is also determined by the advection of warm Atlantic Waters, but to a lesser extent; this effect is especially pronounced in the western sub-area of the Barents Sea. Essentially, the contribution of the local parameters, such as the ice cover in the previous months, the distribution of surface air temperature and the sea ice outflow, is more pronounced in the interannual variations of the ice coverage, while the contribution of climate indices is more pronounced in the changes in the ice area of individual age categories in the Barents Sea.

Most of the models obtained are potentially applicable to forecasting the ice area of various age categories since their efficiency is more than 10 %, which satisfies the requirements for the quality of the long-term forecast method.

The warming process in the Arctic steadily continues and significantly affects the entire regime of sea ice cover development. Most of the sea ice thickness studies are based on numerical modeling and information obtained using satellite radar altimetry such that these estimations require validation by means of contact measurements. However, the comparison of data is difficult due to the irregularity and locality of measurements. This makes contact measurements at polar stations highly relevant. In this study, contact measurements were carried out by drilling for each 10-day period during winter season, they are quite accurate and have a long observations series in the same regime conditions from year to year, allowing one to assess the long-term variability of fast ice thickness. In this study, we analyzed the data series of the fast ice thickness and the surface air temperature at 16 Roshydromet land-based polar stations in the Russian Arctic Seas. The data series were taken into account from the beginning of regular measurements (the end of the 1930s, the year of the beginning varies depending on the station) to 2020 for the period November–May. Observations for the recent 15-year period (2005–2020) are compared with those prior to 2004 (from the 1930s–40s). Since 2005 sea ice thicknesses at the moment of maximum development (maximum sea ice thickness) have decreased by 13 % in the Kara Sea, by 9 % in East Siberian Sea, by 5 % in the Laptev and Chukchi Seas in comparison with the previous period. The sea ice thickness development process has become much slower, transition between the sequential stages of development is shifted by 10–20 days (in some points 30–40 days) later. The surface air temperature is on average 2,7 °C higher than for the previous period at all sea stations. The most significant changes (1.4–6.1 °C) are observed in the autumn season (October–December), all the stations show the lowest difference in the summer months. Averaged over the stations, the sum of the frost degree-days (SFDD) decreased by 14 %; all 15 recent winter seasons can be classified as mild and none of the stations has experienced winters that meet the criteria of severe winter. The frequency of mild winters increased by 36–95 % by stations. The SFDD decline is in good agreement with the changes of the mean seasonal (November-May) and maximum SIT at the stations. In conclusion, it is noteworthy that the recent 15-year period (2005–2020) is distinguished by the mildest conditions.

Age composition is the main characteristic of the ice cover of the Arctic seas in the autumn-winter period. The article presents the results of a study of the seasonal course and interannual changes in the age composition of ice in the southwestern part of the Chukchi Sea in the autumn-winter period for a number of years 1997–2022. The results obtained made it possible to reveal patterns of accumulation and change of ice of various ages.

A well-pronounced seasonal course is observed in the development of the ice cover in the southwestern part of the Chukchi Sea. From the beginning of ice formation to mid-December, young ice (10–30 cm) predominates. From the beginning of January, one-year thin ice (30–70 cm) prevails. From February, first-year average ice (70–120 cm) begins to prevail. At the end of the period of ice cover growth, which occurs in mid-May, one-year medium and thick ice (more than 120 cm) predominate. Their total amount is 71 % of the total ice composition.

Quantitative changes in ice of different ages in the sea waters allow us to determine the average dates of transitions of types of complexity of ice conditions from light to severe. On average, the transition from mild to medium occurs in the first decade of February, and from medium to severe in the second decade of April.

An analysis of interannual changes in the age composition of ice over a 25-year observation period made it possible to establish a trend towards the replacement of old and thick ice by thinner one-year average and young ice.

Previously, similar studies in the southwestern part of the Chukchi Sea were not carried out. The results obtained make it possible to acquire knowledge about the development of ice cover in winter and use it in the development of methods for ice forecasts for shipping.

Modern global climate change is accompanied by an increase in the number of hazardous hydrometeorological phenomena. At the same time, especially rapid warming is observed in the Arctic zone of Russia — 0,71 °С per decade. For this reason, research related to the study of hazardous hydrometeorological phenomena is becoming especially important for the northern territories of Russia, where oil and gas production is currently being intensified, which also increases the main environmental risks. Given the growing interest in hazardous weather phenomena, as well as the need to prevent and reduce negative impact on various sectors of the economy, there is a need for a more detailed study of atmospheric icing. In this study, the aim was to investigate the spatial distribution of ice accretions, which include glaze ice, soft rime, hard rime and wet snow. Also, the work considered the seasonal course of the observed ice accretions and assessed the trend in the number of atmospheric phenomena leading to atmospheric icing for the period from 1966 to 2021. To study the prevailing types of ice accretions, data from visual observations of atmospheric phenomena were used. To study the time trend of ice accretions, the data of 3-hour observations were used. For each of the 7 selected meteorological stations in the Ob’ Bay, the number of cases of atmospheric phenomena was calculated, during which ice accretions of various types could form. As a result, a map of the most common types of ice accretions in the Ob’ Bay region was constructed, which shows that the dominant type of atmospheric icing over the entire territory of the Ob’ Bay region is soft rime. Wet snow occupies from 8 to 30 %. Glaze ice and hard rime are extremely rare. In the cold season, from November to March, soft rime is most often formed, and wet snow accretions in spring and autumn. Based on observational data from 1966 to 2021, trends were estimated in the annual number of meteorological periods during which atmospheric phenomena were observed, potentially leading to hazardous icing. Trends were evaluated using the Mann Kendall test. It is shown that for potentially hazardous cases of atmospheric phenomena causing glaze ice, wet snow and rime accretions, the trends were not significant at the 5 % significance level.

Hydrochemical studies of watercourses and the water area of Blagopoluchia bay (Novaya Zemlya, Arctic, Russia) have been carried out. The concentrations of nutrients in rivers and streams are higher than those in the water area of Blagopoluchia bay. It is shown that the concentration of silicon in constantly flowing rivers is 1–13 μM, the concentration of NO₃ — 0.5–8, for small and temporary streams these values are higher and are in the range of 18–46 μM Si, 1–11 μM NO₃^– . The influence of streams and rivers flowing into Blagopoluchia Bay on the water area of the bay is local and extends to 1 km from the mouth, and does not influence the Kara Sea nutrient content.

Volcanic forcing is one of the major drivers of climatic variability on Earth during the last millennium before the beginning of the industrial era, combined with solar activity, Milanković orbital forcing and greenhouse gas concentration. Large volcanic eruptions (with Volcanic Explosivity Index of 6 or more) eject a huge amount of sulfur dioxide into stratosphere thus reducing the amount of incoming solar radiation. The corresponding cooling may exceed 1 °C and lasts about 5 years. The identification of the volcanic events is carried out with the use of firn and ice core data drilled in the polar ice sheets, while the climatic response to the eruptions is studied with the use of dendrochronology and other terrestrial data, mainly in the Northern Hemisphere. Thus, the reaction of the Southern Hemisphere’s climate to the volcanic forcing is understood to a lesser extent. Here we use stable water isotope data (δ¹⁸O and dxs parameter, dxs = δD – 8 · δ¹⁸O) from 4 firn cores in order to study the temperature change in central Antarctica (in the vicinity of Vostok Station) after 5 major eruptions of the 2^nd millennium of the Common Era: Samalas (1257), Unknown Event 1459 CE, Huaynaputina (1600), Parker (1641) and Tambora (1815). The isotopic composition of the cores was measured in the Climate and Environmental Research Laboratory of the Arctic and Antarctic Research Institute (St. Petersburg) with the use of Picarro L2130-i and L2140-i laser analyzers. We show that a post-eruption cooling in central East Antarctica is about 0.52 °C and lasts for about 5 years. At the same time, the temperature in the moisture source decreases to a lesser extent (0.46 °C), but the cooling lasts longer. We need to emphasize that only through using 4 parallel cores was it possible to significantly reduce the amount of the “deposition noise” in the isotopic records and detect the post-volcanic cooling in central East Antarctica.