A laser method for remote determination of the distribution of capillary and gravity wave slopes on the sea surface is considered. The method illuminates the sea surface from top to bottom with a continuous laser beam and records scattered radiation below the point of incidence of the beam on the sea surface using a video camera. In the presence of intense capillary waves, the beam image has the shape of a light “skirt” that is formed below the point of incidence of the beam on the surface. It is shown that the distribution of capillary wave slopes along the axis perpendicular to the axis of the video camera can be determined from the distribution of light intensity in the cross-section of the light skirt. The distribution of slopes can be estimated almost instantaneously from one video frame in 0.01 s on a surface area of 50 cm2. Accumulating frames and averaging the illumination of the skirt over time τ makes it possible to estimate the distribution of slopes of all waves whose period is less than τ. The article presents the results of theoretical calculations and examples of field measurements in various meteorological conditions. The advantage of the method is the possibility of conducting measurements at almost any time of day, as well as the possibility of measurements from unmanned aerial vehicles.
To study the formation of dense shelf water and subsequent flow along the continental slope in the coastal area of the Cape Darnley Polynya during a specific period of its opening, the small-scale Fluidity ICOM model is used for the first time in a fully nonhydrostatic formulation. The model allows correct analysis of small-scale dynamics of density currents in mesoscale development. In calculations in the computational domain, the bottom topography is close to the actual one; the initial conditions are created in a preliminary experiment and are not specified. To calculate the intensity of intrawater (frazil) ice formation in a polynya, actual parameters of atmospheric forcing are used. The estimates of the values obtained for storm conditions: heat loss from the open water surface of the polynya, the rate of intrawater ice formation (ice productivity) and the intensity of salt fluxes into the water increase sharply (by an order of magnitude or more). In this connection, sharp intensification of convection in the polynya is observed, which enhances baroclinic circulation in the shelf-slope zone. Formed under the polynya, Antarctic shelf water spreads along the shelf and slope in the form of discrete unstable density currents, meanders, which often turn into eddies. In addition to the characteristic baroclinic instability, on bottom irregularities, the density currents also experience hydrodynamic instability, which ensures ventilation of waters on the slope. The bottom irregularities literally determine the cascading dynamics. Direct reliable estimates of the specific and volumetric flows of dense waters on the slope, obtained for conditions when the Cape Darnley Polynya is open, increase by six to seven times. In such areas of the slope in Antarctica, the formation of Antarctic bottom water increases sharply.
The problem of marine litter accumulation is relevant even in remote regions with low anthropogenic pressure, such as the Arctic seas. This study presents the results of three surveys conducted in 2021 and 2023 on the distribution and accumulation of macro- and microlitter in surface waters of the Kara and Barents seas. In 2021, an area of 18.3 km2 was observed, with 695 macrolitter items recorded (average: 4.56 items/km2; pollution density range: 0–210.6 items/km2). In 2023, 108 items were found over 9.4 km2 (average: 8.4 items/km2; pollution density range: 0–24.7 items/km2). Microlitter (1–5 mm) was analyzed based on 45 samples in 2021 (1.679 particles; mean concentration: 0.124 ± 0.383 items/m3; range: 0–1.53 items/m3) and 31 samples in 2023 (184 particles; mean: 0.02 ± 0.02 items/m3; range: 0–0.166 items/m3). Fishing nets were the main contributor to the mass of macrolitter. The average weight of microplastic was 0.0135 g/km2, while macrolitter amounted to 13.4 g/km2, which is 992.6 times higher.
Based on passive microwave remote sensing data, the dynamics of the area of sea ice and ice-free period (IFP) parameters in the East Siberian Sea were analyzed. The average annual start and end dates, as well as the duration of the IFP and rates of their changes for the period 1979–2022, were calculated. Also the features of the spatial and temporal distribution of the IFP parameters were described in the western and eastern parts, as well as in the entire water area, of the East Siberian Sea. From August to October, there is a significant decline in area of sea ice in the East Siberian Sea. This reduction has led to an increase in the duration of IFP. It is shown that during 1979–2022, the duration of he IFP in the East Siberian Sea increased statistically significantly by only 45
The comparison of satellite and visual cloud cover observations over the ocean is a crucial aspect of modern climatology and meteorology. Since 1853, visual cloud observations have been systematically conducted from commercial vessels, forming the basis of the extensive ICOADS dataset, which contains millions of ship-based meteorological reports distributed across the world’s oceans. Initially, cloud cover was measured in quarters of sky coverage, later transitioning to a ten-point scale in the first half of the 20th century. Since the 1950s, the eight-point scale (okta) has become the standard, where eight oktas represent complete cloud cover. The advent of satellite technology in the 1970s revolutionized cloud cover monitoring. Geostationary satellites like METEOSAT provide high-resolution data (0.05° × 0.05°) with multiple hourly images, while polar-orbiting satellites such as EPS/MetOP and POES/NOAA complement these observations. Comparing satellite and visual data presents two major challenges. First, visual observations cover approximately a 13–14 km radius from a height of 12–13 m, requiring proper spatial averaging of satellite data. Second, conversion between measurement units—from okta to percentage coverage—demands careful consideration. The study analyzed two primary datasets: ICOADS visual observations and COMET ed. 2.0 satellite data from 1983 to 2021 in the North Atlantic region. The research methodology included spatial averaging of satellite data, quality control of visual observations, daytime filtering, and exclusion of night observations due to lower accuracy. Analysis revealed several significant findings. Visual observers tend to underestimate cloud cover, sometimes by more than two oktas. Daytime observations showed higher accuracy than nighttime measurements. The research established clear thresholds: values below 6.25
The article studies the state of the cold intermediate layer of Black Sea waters and its transformation over the period 2022–2025. The data of hydrological measurements obtained during expeditions of the R/V Professor Vodyanitsky in the northern and northeastern Black Sea from 2022 to 2025 were used. Vertical water temperature and density profiles at stations with a sounding depth of more than 400 m were considered. Isopycnically averaged water temperature profiles for each expedition were obtained. It is shown that the warming trend of the waters of the cold intermediate layer persists, despite its significant replenishment in 2022. In addition, this trend extends to the underlying layers. In 2024, there is a unique situation of the absence of a cold intermediate layer in the upper part of the main/permanent pycnocline and the presence of a layer with minimum temperatures in the lower part of the main pycnocline. Also, since 2024, there has been a threefold increase in the rate of increase in water temperature in the layer between the 15.6–16.6 kg/m3 isopycnals, i.e., in a layer unaffected by seasonal variability.
In 2025, the Murmansk Marine Biological Institute, Russian Academy of Sciences, as part of the national project “Science and Universities”, completed a series of five marine expeditions on the R/V Dalnie Zelentsy. During the expedition, a comprehensive range of oceanographic and environmental studies was conducted, including meteorological, hydrological, and hydrochemical observations; assessment of biota, water, and bottom sediment pollution; and study of marine ecosystems, including hydrobiological surveys, visual censuses of marine mammals and birds, and bottom ichthyological trawling.
Using GLORYS12 ocean reanalysis and ERA5 atmosphere reanalysis, we quantitatively and qualitatively analyze ocean–atmosphere interactions on a synoptic timescale through water mass transformation rate and buoyancy flux in the Labrador Sea. Calculated for the entire World Ocean over 31 years, from 1993 to 2023, the buoyancy flux dataset is used to derive average climatological values for the North Atlantic. Based on buoyancy flux data, water mass transformation rates in the Labrador Sea are calculated and the mean long-term distribution of transformation at different water densities and long-term transformation dynamics are considered. Bandpass filtering highlights the importance of synoptic timescale in water mass transformation in the Labrador Sea. Cases with large increases in water mass transformation rates, which are related to synoptic atmospheric dynamics, are considered in detail, using January–March 1993 as an example.
The article discusses the preliminary results of the PaleoRAP-2025 expedition to the Bering Sea and adjacent Pacific Ocean related to bottom sediment color mapping, clay pebble findings on the seafloor, and measuring hydrogen sulfide content in water and bottom sediments.
This paper examines the eddy structure of surface and bottom currents that form in an eastward meandering flow over non‑axisymmetric seabed topography at different meandering phases, drawing an analogy with the eastward‑flowing Mid‑Mediterranean Jet (MMJ). The topography includes the Eratosthenes Seamount, located in the southeastern part of the deep-sea hollow in the Levantine Basin south of Cyprus. Different modes of the dipolar vortex structure, consisting of a topographic anticyclone (the Cyprus eddy) and a smaller local topographic cyclone, are described. The influence of different meandering phases of the background flow on the appearance and size of two separate topographic eddies, as well as on the trapped stationary Rossby wave formed behind them, is established. The solutions are based on the classical analytical theory of topographic eddies on the β-plane [3, 4] and complement earlier studies [1, 2, 17, 18] explaining the variability of the dipolar vortex structure south of Cyprus. The results of the study are consistent with the CMEMS-MED-PUM-006_013 reanalysis data.
The paper analyzes tides in the La Perouse Strait based on modeling data. The calculations were performed using the ADCIRC model on a high-resolution unstructured grid. The quality of modeling was assessed based on instrumental observations of sea level at coastal stations. When comparing the modeling results with measurements, the correlation coefficient is 0.92–0.98 and the root mean square error is 0.04–0.07 m. The highest tides are observed in northern Aniva Bay: 1.6 m. All four types of tides are identified in the La Perouse Strait. Harmonic analysis of the tidal harmonics M2, S2, K1, and O1 made it possible to refine the spatial structure of their amplitude–phase parameters. Semidiurnal tides come from the open part of the Sea of Okhotsk, and the phases of both harmonics change little in the area of the strait. Diurnal tides have amphidromic points located at the narrowest point of the strait between Cape Crillon and Cape Soya. The spatial distribution of their cotidal lines indicates their eastward distribution along the Okhotsk coast of Hokkaido.
The results of the investigation into the environmental consequences of the December 15, 2024 accident involving the tankers Volgoneft-212 and Volgoneft-239 indicate that the Anapa area was the most heavily polluted. The decrease in hydrocarbon concentrations observed 2.5 months after the accident was attributable to mechanical weathering onshore and in the water column, as well as to microbial degradation. As a result, concentrations of chloroform-extractable organic matter, including low molecular weight alkanes and polycyclic aromatic hydrocarbons (PAHs), declined. The hydrocarbon composition of suspended particulate matter in near-bottom waters and of bottom sediments remained predominantly petrogenic. The area remains affected by residual petroleum hydrocarbon pollution.
An analysis of spatial distribution of mean arithmetic concentrations of CaCO3, Al2O3 and SiO2 has been done for the Indian Ocean Pleistocene sediments based on reports for International Project for Deep-Sea Drilling cruises and other references. To reach these goals we have compiled schematic maps of pointed sediment forming components, of Al2O3 and SiO2 in noncarbonate matter, and also of ratio SiO2/Al2O3 distribution. The methods of such compiling have been described. We have revealed conclusions about spatial peculiarities of carbonate and silica accumulations, and also about accumulation of terrigenous matter in the Pleistocene time. A comparison of these peculiarities with the Recent time gave an opportunity to make the conclusion about close similarity of the main natural zonalities combination in the Recent and Pleistocene times.
The article presents data on the content and composition of hydrocarbons (HCs): aliphatic (AHСs) and polycyclic aromatic hydrocarbons (PAHs) in waters and Holocene sediments (bottom grab and undisturbed cores 0–30 cm) of the southwestern Kara Sea (part 1 of cruise 89 of the R/V Akademik Mstislav Keldysh, September 2022). In waters, the distribution of HCs is determined by hydrological factors and their input in fluid flows in shallow waters. In bottom sediments, the distribution of HCs, in contrast to Corg, does not depend on their lithotype, since in the gas-saturated zone, high-molecular HCs are formed along with methane. This leads to an increase in the proportion of AHCs (>1
The study presents the implementation of the third-generation spectral wave model WaveWatch III for the White Sea. The computational domain includes the White Sea, Barents Sea, and part of the Norwegian Sea. Model validation against satellite observations showed high agreement (correlation coefficient 0.92, root mean square error 0.32 m). The highest long-term mean wave heights ( 1.5 m) and wavelengths (up to 60 m) occur in the White Sea Voronka under the influence of the Barents Sea. Mean wave periods reach 4.2 s. Over 42 years, mean annual wave heights increased by 0.3 m. Storm activity was estimated using the peak over threshold method for thresholds of 2–5 m, with an average of 71 storms per year for Hs > 2 m. The results indicate strong spatial variability of the wave regime and emphasize the importance of regional zoning in storm analysis.
The material was collected in the course of the 95th cruise of the Akademik Mstislav Keldysh research vessel in the eastern part of the Barents Sea and northern and central parts of the Kara Sea from June 26 to July 17 in the seasonal ice meltdown period. Three types of Phaeocystis pouchetii free-living cells were found in the samples: two flagellate forms (microzoospores of 3–4.5 µm in diameter and cells of 5–6 µm in diameter) and larger nonmotile cells of 5–6 µm in diameter. An average for water column species abundance varied from 270 × 103 to 4756 × 103 cell/L at a biomass from 25 to 826 µg/L. Phaeocystis was found to a depth of 75 m. In most cases, a species cell concentration was maximum (5.5–21.0 × 106 cell/L) at the density transition zone or below, with higher nitrates and a salinity not less than 34 PSU. The data obtained made it possible to outline the southern boundary of P. pouchetii distribution in the Kara Sea. The species was not observed in the shelf area with a depth of less than 256–400 m. A salinity of the upper mixed layer in the shelf area where P. pouchetii did not penetrate was 32.6–33.2 PSU.
Analysis of satellite-derived sea surface temperature data from 1998 to 2023 reveals distinct spatiotemporal variations in thermal conditions along the coast of the Iturup Island. The interannual variability is most pronounced in summer temperature maxima with fluctuations, reaching approximately 5°C. Decomposition of temperature fields, using empirical orthogonal functions, identifies spatially segregated zones influenced by the Sea of Okhotsk and Pacific waters. The temporal modes reflect a notable climatic shift around 2012–2013, which testifies to a significant reorganization of the thermal regime during the Pacific salmon fishing season. While extreme temperature anomalies in waters adjacent to the Iturup Island are generally rare, they were observed across nearly the entire study area in 2023. The correlation analysis between sea surface temperature and catch data for pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon suggests that thermal conditions during juvenile migration and prespawning periods may affect interannual fishery dynamics in the Iturup Island region.
Video transects were obtained using a towed underwater vehicle “Videomodule” in Blagopoluchiya, Tsivolki, Oga, Sedov, and Rusanov bays (Novaya Zemlya Archipelago, the Kara Sea) in 2016–2024 as part of the “Ecosystems of the Siberian Arctic Seas” project. A quantitative analysis of the dominant megafaunal organisms along with the description of their communities were conducted. In 2016, the communities dominated by Ophiacantha bidentata and suspension feeders prevailed in the outer parts of the bays and on the slope on dense and rocky bottoms. In the inner parts of the bays on silty sediments the communities were dominated by Ophiopleura borealis. The current state of the megafauna in all studied bays differs drastically from the community structure observed ten years ago. These changes are assosiated with the snow crab invasion. The megafauna abundance dropped in 10–30 times, while the proportion of snow crabs in terms of abundance increased to 30–80
During cruise 137 aboard the R/V Professor Vodyanitsky in fall 2025, comprehensive geochemical studies of methane gas seeps were conducted, as well as an assessment of the ecological state of coastal waters in the vicinity of medium and small rivers of the northeastern Black Sea coast. New information on the gas-geochemical conditions of the Black Sea region was obtained.
The materials of measurements of long-wave oscillations obtained from a Tsunami Warning Service recorder in the port of Posyet (2013‒2025) and two autonomous stations in Vityaz Bay (July–October 2009) in Posyet Bay were analyzed. It was revealed that in the spectra of the records in Posyet peaks at periods of about 91, 32, and 18.5 min and at a period of 48 min in Vityaz Bay are significantly distinguished. They were present almost continuously, except for the period from mid-October to mid-November 2024, when intense chaotic variations prevailed in the range of 30–60 min. The intensity of these peaks increased during hazardous marine phenomena, such as storm surges and tsunamis, which suggests a connection with the resonance features of Posyet Bay and their importance in the transformation of the wave field under various weather conditions. Numerical modeling revealed that the complex configuration of the bay makes it difficult to apply traditional seiche classification. Thus, even the low-frequency component with a period of about 91 min, due to the shelf resonance, meets the usual characteristics of such only in the outer part of the bay, up to the foreland that separates the shallow Novgorodskaya and Ekspeditsii bays, in the water area of which its own peaks and nodal lines are distinguished. The mode with a period of 49 min has the character of a single-nodal transverse seiche (with peaks at the Gamov and Suslov peninsulas) only in the part of the outer water area beyond the Reid Pallada Bay. The spatial structure of the eigenmode with a period of about 33 min in the seaward is similar to the two-node longitudinal seiche. Both of these components are characterized by a large number of nodes and nodal lines in the inner basin with small amplitudes of oscillations. The zeroth mode with a period of about 70 min plays an important role in the formation of the wave field, mainly in Reid Pallada Bay, but it is weakly expressed in the area where the level fluctuation recorders are located, which makes it difficult to assess its real role based on the observation data.
