When modeling processes in the ocean, the issue of describing turbulent exchange inevitably arises. Today, there are numerous methods for parameterizing turbulence in the upper layer of the ocean. The most common and established closure methods for hydrodynamic equations are considered by introducing turbulent kinetic energy and turbulent mixing length, and a formulation of the ocean general circulation model is provided. A series of experiments were conducted, each using different combinations of equations for turbulence parameterization, which also utilized data from The Copernicus Global 1/12° Oceanic and Sea Ice GLORYS12 Reanalysis and HYCOM + NCODA Global 1/12° Reanalysis to describe the advective components of scalar quantities. The comparison of model data was made with observational data obtained from automatic marine stations of the Pacific Marine Environmental Laboratory. It is shown that using more complex forms of the turbulent kinetic energy equation, as well as additional equations for calculating the turbulent mixing length, does not lead to unambiguous improvements in results. It is also shown that the same combinations of equations can yield opposite results in terms of quality.

Time series of water temperature and conductivity obtained over three years of continuous measurements at seven autonomous moored stations north of the Severnaya Zemlya archipelago located in the Arctic Basin of the Arctic Ocean were analyzed in combination with numerical modeling to investigate the spatiotemporal variability of temperature and salinity in the intermediate layer of Atlantic-origin waters. These waters propagate along the Eurasian continental slope within the Arctic Boundary Current (ABC). Within 85 km of the shelf edge, three distinct branches of Atlantic Water (AW) transport were identified, each characterized by a unique origin history of origin that shapes the variability of its thermohaline properties. The most energetic mode of temporal variability at all stations is associated with oscillations with a period of approximately 12 months. The amplitude of these oscillations decreases with increasing distance from the shelf edge, while their phase differs among the AW branches. Numerical modeling indicates that, in the study region, the typical phase–distance relationship observed in the western Nansen Basin is disrupted by the large-scale input of cold, freshened water through the St. Anna Trough.

This study presents oceanographic observations from the R/V Dalnie Zelentsy along the Kola Section (2017–2023), focusing on the northern Polar Front during autumn, winter, and spring. Sea ice anomalies were estimated using data from the World Data Center for Sea Ice (AARI WDC Sea-Ice). Observational data near the Marginal Ice Zone were compared with temperature and salinity fields from global oceanographic datasets, including MERCATOR PSY4QV3R1, CMEMS GLORYS12v1, and TOPAZ5. High-gradient temperature and salinity zones were observed at varying distances from the ice edge along all sections. Over the past three decades, the western Barents Sea has experienced a steady decline in sea ice cover. The northernmost Polar Front along the Kola Section ranged from 48 to 290 km from the ice edge, with temperature gradients of 0.10–0.20 °C/km and salinity gradients of 0.012–0.025 psu/km. The frontal zone width did not exceed 55 km. Among the assessed data products, MERCATOR PSY- 4QV3R1 showed the highest correlation with in situ measurements.

The article examines the impact of the construction of a marina on the lithodynamic processes in Gelendzhik Bay, a closed water area with a complex sediment balance. Historically, the bay was a closed system, but active hydraulic engineering (artificial beaches, port facilities) disrupted the natural morphodynamics. An integrated approach combining numerical (SWAN, Wave Watch III models) and physical modeling on a scale of 1:100 has been applied to assess the effects of anthropogenic impact.
Physical modeling has shown that the port facilities form local erosion zones./sediment accumulation. The results of experimental studies qualitatively confirm the conclusions of numerical modeling. Despite the local changes, the port does not significantly affect the overall sediment transport. The study highlights the need for an integrated approach to modeling lithodynamic processes.

The development of the physical foundations of remote diagnostics of areas of plastic pollution of reservoirs has now become highly relevant due to the increase in anthropogenic pollution of the World Ocean. The pollution is largely related to the polyethylene (PE) films, which can affect to variability of the radar scattering signal when probing the sea surface, which can be used to diagnose plastic areas. PE films are often located in the near-surface layers of water, rather than floating on the surface, despite the fact that their density is usually less than the density of water. This paper presents a numerical study of the dynamics of a small floating PE film in the field of surface waves. The open source software “OpenFOAM” was used as a numerical modeling tool. It was found that the film floats in the absence of waves, but if there are any surface waves, it can sink, float, or be in the equilibrium at some depth. The detected effect indicates the occurrence of an additional force in a fast oscillating wave field, which is directed against buoyancy forces and depends on the steepness of the wave and the depth of the initial film location.

The possibility of increasing the efficiency of spatial processing of tonal signals in acoustic waveguides with wind waves is investigated. It is shown that preliminary frequency filtering of the signal in a narrow band in combination with known spatial processing algorithms allows to significantly increase the gain of the horizontal antenna array (AA). The main idea of the proposed spatio-temporal signal processing is to suppress the incoherent component of the acoustic field during frequency filtering of the signal. An algorithm for calculating the correlation matrix of the signal based on the transfer equation for the spatio-temporal coherence functions of complex amplitudes of acoustic modes is proposed. The results of numerical modeling of the gain factors for various signal processing algorithms in a sound channel with winter-type hydrology are obtained. The dependences of the gain factors on the distance, wind speed, bottom parameters, noise model and AA orientation are analyzed. The main attention is paid to comparing the results with and without frequency filtering.

To estimate the range and depth of noisy sources, it is recommended to use vertical antennas and processing algorithms that take into account the properties of the waveguide. Below, it is shown that a vertical antenna can estimate the range and depth of a source in the deep sea over a sufficiently large range of distances and in the case when full information about the signal model is not used, but the information is processed simultaneously using two complementary algorithms that take into account the angles of arrival of beam signals in the vertical plane and the interference of sound pressure at the antenna aperture.

The aim of the article is a quantitative analysis of the influence of the interrelation between the physical parameters of scattering of intense disturbing signals and the parameters of “fast” algorithms on the resolution capability when detecting weak signals. The study is conducted using model data, where the transfer function of the medium for the disturbing source contains a random component characterized by a coherence coefficient and correlation intervals in space, frequency, and time. In the model experiment, the parameters of the generated scattered fields are known, which allows for controlling the relationship between the field parameters and the parameters of the “fast” algorithms used in the resolution of weak signals. The results of measuring the parameters of the input mixture components, highlighted by the first and second eigenvalues and eigenvectors, are presented. Pseudo-location reliefs are also provided, and trajectories are constructed which reveal the detection of a weak signal crossing the trajectory of a strong signal, depending on the number of adjusted eigenvalues. The quality criterion is based on the level of the leaved scattered component and the angular masking zone of the weak signal after the adjustment of one or several eigenvalues. An analysis of six initial data variants showed that when using sample elements differing in frequency, the possibility of resolving weak signals depends on the ratio of the adaptation interval and the correlation interval of the distortion by frequency.

The main directions of development of the Northern Sea Route for the period up to 2035 are analyzed. The results of an analysis of the navigation of large-tonnage vessels during summer navigation on the routes of the Northern Sea Route, as well as the parameters of lateral deviations from the recommended routes and the width of their lanes are presented. The state and prospects of development of the Russian orbital constellation of spacecraft solving the problems of remote sensing of the Earth in the Arctic are considered. The forecast of the expected results of the application of existing and prospective space systems in solving the problems of monitoring navigation on the Northern Sea Route has been carried out.

The aim of the study is to develop a methodology for estimating the average lake depth based on remote sensing data of ice conditions using methods of modelling thermohydrodynamic processes in a freezing water body. The primary tool f or accomplishing this goal is the FLake — lake hydrophysical model. Using meteorological data from the ERA5 reanalysis for the coordinates of the selected water body, the model calculates the time of ice formation on the water body at different values of its average depth. Based on remote sensing data, the date or time interval of water body freezing estimated. If data for several years are available, the depth of the water body specified by averaging the values for each year. At discreteness of satellite images with an interval of several days, the range of average lake depths corresponding to the time interval between satellite passes over the water body is determined. Information on the onset of ice phenomena was obtained based on the results of thematic interpretation of Sentinel‑2, Landsat‑7, 8, 9 satellite images for the period from 2016 to 2023. The methodology tested on four groups of morphometrically- studied lakes located in permafrost zone of Eastern Siberia in the Republic of Buryatia and Transbaikal Territory. The results of approbation showed a satisfactory correspondence between the calculated and measured values of the average depth of the lakes under consideration. The quality and quantity of satellite images in the study region limited the accuracy of the proposed methodology. The prospects of the methodology lie in the possibility of fully remote assessment of water resources of poorly studied regions of the country.

Field measurements of the characteristics of the bottom-reflected lidar echo signal were conducted in the waters of Bechevinskaya Bay. The studies employed the APL‑3 airborne polarization lidar (sounding pulse energy of 45 mJ, receiving optical system diameter of 100 mm, and system response function duration at the 0.5 level of 10.8 ns). The depth range during the investigations varied from 3 to 22 m, while the flight altitude ranged from 500 to 1200 m. The hydrooptical characteristics of the bay waters were assessed based on lidar sounding data. For the analysis of field measurement data, areas with similar values of the lidar attenuation coefficient were selected. The results of field experiments demonstrated that the relationship between the magnitude of the lidar echo signal and the length of the sounding path for water layers and the seabed is more complex than what is suggested by the conventional form of the lidar equation. The introduction of an additional term into the lidar equation, which defines the dispersion of the irradiance distribution in the cross-section of an infinitely narrow beam of light passing through a water layer of a given thickness, allowed for a more accurate description of the obtained experimental dependencies. The registered effect must be taken into account when designing lidar systems, as well as during the processing and analysis of lidar survey data.