The results of studies of distant fields of wave disturbances on the surface of a heavy fluid from a fast-moving oscillating source are presented. A method is developed for the numerical solution of the equation for the spreading of an oil spill on the sea surface, which correctly describes the movement of the contact boundary of the spill. The estimates of the variability of the characteristics of the sea surface temperature in the frontal zones of the Kara Sea from July to September in 2007 and 2011 are obtained. Based on a statistical analysis of data from measurements of short-period internal waves in the deep-water region of the Barents Sea, it is shown that in the range of 20—60 min there is a synchronous relationship between temperature and light attenuation coefficient with coherence above 0.9. The principles of formation and achievable parameters of high-speed radar images of the sea surface obtained from stationary, aviation and space carriers are considered. Based on observational data during the period of early-spring under-ice convection development in Lake Vendyurskoe, the dynamics of the mixed layer is described and its integral parameters are estimated. In the framework of a brief review of the state of knowledge about the study of hydrophysical processes and ecosystems of large lakes and the White Sea is argued that the resources and capacities of various organizations need to be united to arrange integrated experiments and build models for dealing with the tasks of the rational management of internal waters. Based on the solution of the problem of changes in the regional climate of the Kara Sea, it is shown that the contributions of tidal changes in sea temperature and level to their formation turn out to be significant, and the contribution of tidal changes in salinity is considerable. In the framework of a systematic review of the major milestones in the development of ocean hydrophysics, the names of the leading figures of Russian science, who created its foundations and scientific schools that have been active for many decades and have had world-class achievements in their work, are named.
This issue opens with an article on physical mechanisms for the formation of informative features of an acoustic echo signal reflected from an underwater object and the results of experimental recognition of an object’s material by the method of hydroacoustic echolocation. Next, the influence of ultra-low-frequency fluctuations of underwater noise emissions from ships on the possibility of extracting of signal amplitude modulation existing in the frequency band of pitching is analyzed. The joint object recognition and distance determination are considered comparing the pressure spectral density of the noise signal with the samples of the spectral pressure density of the noise signal of the objects stored in the database. It is shown that the source flow pulsations significantly affect the structure and internal dynamics of the intrusion flow in a stratified fluid. Based on the calculations of wind wave parameters, an assessment of the energy resources of wind waves in the Baltic Sea has been carried out. Using data of microstructure measurements, the mixing hot spot at the Słupsk Sill was found to be responsible for approximately 5% of the inflow water salinity decrease on route from the Arkona Basin to the Gotland Deep. A one-dimensional model of the boundary layer above the waves is formulated and calculations illustrating the features of the wave boundary layer are carried out. When modeling the long-wave impact on hydraulic engineering constructions, it was found that in non-hydrostatic solution at the entrance to narrowness, on raising the bottom, an increase in vertical velocities causes a local level rise, and that the dynamic component of pressure can modify currents on elements of the constructions. New data on nutrient loads at the small unmonitored rivers of the Gulf of Finland were analyzed and it was shown that to implement the nutrient abatement recommendations of the HELCOM a further reduction of 2084 t of N/a and 202 t of P/a from Russia is needed. Using the example of the White Sea population of the harp seals, the possibilities of improving the technology of airborne for calculations of marine mammals based on satellite microwave radiometry data are considered. The issue ends with two articles devoted to the most important areas of work of Professor K. S. Shifrin, an outstanding Soviet scientist in the field of optics of the atmosphere and the ocean.
Analysis of the monthly average data of the Baltic Sea temperature on the surface and various depths showed significant growth over the past decades. Against this growth, temperature oscillations were registered. The relationships between these oscillations and the El Niño, the North Atlantic Oscillation and the North Atlantic Current are shown. Temperature and salinity variability in the upper ocean layer in the Arctic basin are analyzed. Since the mid-1990s, multidirectional changes in the thermohaline parameters have been observed in the western and eastern parts of the Arctic basin. One of the main reasons for the desalination of surface waters in the eastern Arctic is a reduction in the area of perennial ice and its replacement by seasonal one against the background of increased riverine water discharge and change in the atmospheric circulation over the Arctic. The salinization of surface waters in the western Arctic is associated with an increase in the supply of saline Atlantic waters from the Fram Strait. Generalized results of a study on submesoscale eddies’ surface manifestations in the Barents, Kara, and White Seas based on the analysis satellite radar images during ice-free periods for several years from 2007 to 2012 ae presented. Comparison of the positions of eddies’ surface manifestations, the frontal zone positions, and the bottom topography showed that the frequent occurrence of eddies is predominantly observed near and within the areas of the variability of the frontal zones. Mesoscale eddies of the Lofoten Basin of the Norwegian Sea were studied with satellite observations. In the Lofoten basin, there are two predominant mesoscale eddy systems. This fact may reflect two different mechanisms of eddy generation. The first one is the separation of eddies from the Norwegian current during its meandering. The second one is the direct generation of eddies inside the Lofoten Basin. The methodology and results of ice maps processing from the AANII archive for the period from 1998 to 2018 are presented. Ice navigation conditions’ parameters that affect the probability of accidents are studied.
The issue addresses the matters of numerical modeling of ocean dynamics, analyzes the data of field experiments on current velocities, and discusses applied problems of ocean optics and hydroacoustics. The effect of various parameterizations of the atmospheric boundary layer on the quality of reproduction of the wind waves evolution is studied. The results of numerical modeling of the tsunami wave evolution in the Azov-Black Sea basin for the sources corresponding to tsunamigenic underwater earthquakes are discussed. The principal possibility of operational forecasting of tsunami arising in the region of the central Kuril Islands using the data of the level measuring station closest to the centers of tsunami generation in the presence of seismic noise is shown. Based on a three-dimensional numerical hydrodynamic model, the propagation of microplastic particles in the Neva Bay and in the eastern part of the Gulf of Finland are studied. The possibility of restoring the barotropic component of hydrostatic pressure using the measurements of current velocities in the bottom layer is considered. Based on data from contact measurements since 1960 until now, the variability of current velocities in the Black Sea at depths below the main pycnocline is analyzed. The generalized results of ship and satellite studies of the bio-optical characteristics of the surface layer in the Arctic seas are presented. The characteristics of a light impulse propagating in water, modulated by a radio signal with a frequency linearly varying in time, are studied. A compensation approach is proposed aimed at eliminating methodological errors in measuring the spectral light attenuation coefficient in sea water. Estimates of the energy of the probe impulse required for aviation lidar bathymetric surveys of coastal waters from various heights are given. Analytical dependences are obtained that determine the patterns of attenuation of the sound pressure of low-frequency signals with increasing distance formed in the waveguide in the zones of interference maxima. Based on the beam model using experimentally recorded signals on a horizontal, long towed antenna, an example of the implementation of natural processing of hydroacoustic fields is given. It is established that the first footstock after the catastrophic flood of the Neva in 1715 was built near the Admiralty, and not near the Peter and Paul Fortress.