The issue presents researches of the ocean dynamics on the basis of physical and mathematical model approaches and extensive material of in situ observations, application-oriented tasks of hydroacoustics are considered, georisks at construction of sea pipelines are discussed. A review of oceanologic models of not hydrostatic dynamics for the last several decades is provided. The modulation phenomenon of short infragravity waves by the tides on the shelf of Sakhalin Island is analyzed. The effect of subinertial sea level atmospheric pressure fluctuations on the inflow intensity of the surface Atlantic waters through the Strait of Gibraltar and its impacts on the dynamics of the Alboran Sea is studied. The eigenvalue spectra for a model problem describing formation of the large-scale intrusions in the Arctic basin is considered. The Mapping of the Baltic Sea by the types of density stratification in the context of dynamics of internal gravity waves is discussed. The flooding mechanism in the Kuban River Delta, caused by the rise of the level of the Sea of Azov due to atmospheric impact, is investigated with the use of numerical modeling. the effect of vertical heterogeneity of acoustic properties of sea ice on phase of reflection coefficient of acoustic low-frequency harmonic plane wave at its normal incidence on sea water-ice interface is investigated by a method of model experiment with application to the task of remote measurement of the Arctic Sea ice cover thickness from under water. The verbal behavior of beluga whale Delphinapterus leucas acoustically stimulated by noise-like signal during demonstration of video images is studied. A methodical approach to risk assessment in the construction and subsequent operation of the offshore part of pipelines associated with the manifestation of natural and other factors is suggested.
In the special issue new results on the study of internal waves in the Baltic Sea are presented, including calculations of the transformation of internal solitons for real sea hydrologic conditions. The velocity fields calculated with a very high horizontal resolution (232×232 m) in the Gulf of Finland during the summer upwelling are used to calculate the advection of floating Lagrangian particles and to study their behaviour and clustering at short and long advection times of advection. A model approach is proposed to assess the intensity of coastal erosion on the shores of the Kotlin Island and to choose the particular method of artificial sand nourishment in order to maintain the sandy beaches. It is shown that in 1994—2015 the values of species’ richness and Shannon index (information entropy) in the resort zone of the eastern Gulf were muchlower than in the Neva Bay due to not only the changes in salinity, but also the more intense pollution of the Neva Bay. Based on the national monitoring data from 2011—2016, it was demonstrated that the entire Estonian marine area is affected by eutrophication. An approach is proposed for the assessment of biological effects of environmental chemical stress based on using the method of physiological loading on bivalve molluscs and anti-orthostatic test in crustacean.
The first regular paper of the issue gives an overview of studies of bottom water flow in the Vima channel in the South Atlantic, where high current velocities (up to 60 cm / s) are observed. On the basis of a comparison of the model solutions, it is shown that the tides contribute noticeable in the surface resultant circulation of the Kara Sea. A deterministic-stochastic modeling system describing mass transfer in the catchment-reservoir system is effectively used in solving problems of abiotic processes assessment in the system, as well as of forecasting the impact of climate changes on water bodies. A 40-year model run with the eco-thermohydrodynamic model of the Kara, Barents and the White Seas shows that the region-integrated annual primary production and the total ice area vary in anti-phase. A method is proposed for estimating the content of suspended and dissolved organic matter from the attenuation index of light at two wavelengths, and an evaluation of these characteristics in the surface layer of the Black Sea using data of 2016 was carried out.
The issue presents papers on the ocean optics problems, including the fundamental studies and applied design. The issue is dedicated to the 100th anniversary of the outstanding Soviet scientist in the field of atmospheric and ocean optics, Prof. K.S. Shifrin. The twelve articles relate to different areas of the hydro-optical researches. The problem of propagation of the sinusoidally modulated light beams in a scattering inhomogeneous medium, which solution opens up additional possibilities for selective diagnostics of macro-inhomogeneities in the scattering medium, is considered. The results of the study of the reflectivity of melting Arctic ice, important for the problem of global warming in the Arctic, are considered. The data on various aspects of the variability of the optical characteristics of different water basins (the Gorky Reservoir, the Kara and Black Seas) are presented. The new algorithms of determination of the spectral-energy characteristics of a random field of internal waves by the lidar echo signals are described. Various aspects of the use of satellite ocean color data are considered. New possibilities of the method of specular points to estimate the ”instantaneous” relief of the sea surface and the algorithm for reconstructing the slope vector of the wavy water surface are discussed. The effectiveness of a new optical complex for measuring the spectral radiance reflectance from board of the moving ship is demonstrated.
This issue opens with the last article of Igor Vyacheslavovich Tkachenko who suddenly left us, in which, using numerical experiments with а non-hydrostatic “water – air” model, a considerable non-stationarity of the flow around an ellipsoid of rotation was revealed. In the following article the statistics of wind wave spectrum peakedness based on hindcasting for some seas around Russia were calculated. The results of studies of acoustic noise and multipath parameters in the Arctic shelf seas are discussed. Аn analysis of trends in the components of ocean-atmosphere moisture exchange based on data from existing archives showed that after 2011 the increase in moisture content outpaces the growth in air temperature by 1 year. The calculated anomalies of the vertical and horizontal components of the magnetic field of the spreading zones in the North Atlantic are presented. It was established that the existence of an underwater plume, observed from space near Sevastopol in the area of the deep-water runoff, is a consequence of the emergency state of the wastewater discharge system. A deterministic-stochastic modeling system describing mass transfer in the catchment-reservoir system is developed. Estimates are obtained of the frequency of occurrence of extreme heights of short-period internal waves and the associated bottom current velocities and bottom pressure variations in the shelf areas of the White, Barents and Okhotsk seas. The data of observations of internal waves and the results of calculations of the transformation of internal solitons in the Baltic Sea with regard to real hydrology are discussed. The edge-trapped waves near the southeastern coast of Sakhalin Island have been observed, which are the cause of the formation of alternating zones of erosion and accumulation of sediment. It was found that the first the tide-gauge after the catastrophic Neva flood in 1715 was constructed near the Admiralty, and not “on walls” of the Peter and Paul fortress. The St. Petersburg Baltic Eutrophication Model (SPBEM) has been improved by incorporating dissolved organic nitrogen and phosphorus. The solution of the phase transition problem for gas hydrate — gas + water system in the presence of a metallic heat source is obtained, which can be used when interpreting the results of measurements in hydrate-bearing sediments using the needle probe method.