The results of numerical modeling of rising of bubbles and solid spheres with a diameter of 1 to 20 mm in water are presented. The analysis is based on the numerical solution of the complete system of Navier—Stokes equations for a two-phase medium in a three-dimensional formulation in an implicit manner. The interface gas-water boundary is automatically monitored by the method of allocating the volume fraction. The motion of solid spheres is modeled using the method “Chimera”. Particular attention is paid to the study of local physical characteristics of motion process. Comparison of average calculated rising velocities with experimental data is carried out. The periodic (zigzag or spiral) character of the trajectory of moving bubbles associated with changing their shape and with the formation of a characteristic turbulent trace is shown. The correlation of the velocity of bubble rise with the forces acting on it is obtained. The tendency of change of a rise trajectory in process of increase of number of Galileo is revealed for solid spheres.

The linear trends in the components of ocean-atmosphere moisture exchange (evaporation, precipitation and their difference — net evaporation), air temperature, and sea surface temperature are estimated based on the data of the archive Reanalysis-2 and the data from the REMSS satellite archive on integral atmospheric total precipitable water for the period of 1988—2016. An intensification of growth of moister exchange components has been observed since 2012. The results showed that the amount of precipitation over the global ocean is growing faster than evaporation by 1.1 mm/year, which is 35 % of the actual global sea level trend (3.1 mm/year). The analysis of dimensionless trends showed that the trend in total atmospheric precipitable water is almost twice as high as the trend in air temperature over the global ocean. This means that the longterm (trend) changes of precipitable water depend primarily on the vertical air-ocean moisture exchange and not on the global warming. Since 2012 the growth of amount of precipitable water is 1 year ahead of air temperature. Thus the characteristics of atmospheric total precipitable water is not only a key consequence of the global warming process, but is also its forming factor.

This paper discusses the results of observations of the height of short-period internal waves conducted in summer seasons of the years 2010—2017. The work was carried out in the Western Solovetskaya Salma, on the border of the Basin and the Gorlo Strait, in the Bay of Dvina in the White Sea; near Harlow Island, the island of Harlov, near Cape Teribersky in the Barents Sea; near Cape Svobodny, above the shelf break near the Kuril Basin in the Okhotsk Sea. The duration of measurements in each area varied from 25 to 80 hours. It is established that waves' heights have everywhere the highest repeatability 1—3 meters. Intensive internal waves (higher than 10 meters) are regularly observed in the areas of Western Solovetskaya Salma in the White Sea and near cape Svobodny in the Okhotsk Sea. Estimates of the probability of occurrence of extreme internal waves, which can be observed once a month during the warm season, are made in the assumption of the steady-state of wave-forming factors. It is established that intensive internal waves can be observed in all seas, and in the White and the Okhotsk Seas the heights of extreme waves can exceed 15 meters once a month. For areas where waves with extreme heights were recorded, the calculation of the bottom flow velocity and variations of bottom pressure were made. It is found that the variations of bottom pressure caused by extreme internal waves varies from 120 to 380 Pa, and flow velocities induced by waves vary from 7 to 17 cm/s. Accordingly, variations of the bottom pressure will not have a significant impact on offshore structures, and flow associated with extreme internal waves are able to erode silt and sand soils. However, working together with tidal flows, such flows can contribute to significant transport of sediment, which can have an impact on the stability of underwater hydraulic structures.

The materials of wind-wave instrumental records obtained as a result of a field experiment in the area of the Izmenchivoe Lake spit (South-Eastern coast of Sakhalin Island) are analyzed. This experiment included setting up of three wind-wave and level gauges ARW-K10 in June—October 2007. During this period, several storms were recorded. One of them, occurred at September 25—26, related to extreme storms (the significant wave height exceeded 3.5 m, the maximum height reached 6 m). At different stages of its development, the ranges of periods were identified, at which the phase shift between the stations S3 and S8 located along the normal to the coast equaled zero, that corresponds to the edge-trapped waves propagating along the shore. These ranges (137—186 s and 68—82 s) corresponded to intervals with a linear phase change between stations S18 and S8 located parallel to the shoreline, which allowed us to estimate the velocity   of long wave propagation equal to 1.8 and 1.1 m/s. The corresponding wavelengths were about 300 and 80 m, that is consistent with the typical quasirhythmic forms of the coastal relief in the studied area. The distance between the large forms (megafestones) was about 1.2 km, that is much larger than the typical lengths of the edge waves. During the storm peak, the average for the 4-hour interval amplitude of the edge waves in the indicated period ranges was 5.8 and 4.7 cm for the nearshore and 2.5 and 2.1 cm at the remote stations. The particle velocity estimates for station S3 were about 30 and 40 cm/s, respectively. High velocities of currents having opposite directions at distances of about 150 and 40 m are the cause of the formation of alternating zones of erosion and sediment accumulation.

St.-Petersburg model of eutrophication (SPBEM) has been modified for improving description of organic matter as a part of the nutrient biogeochemical cycles. The dynamics of labile and refractory fractions of dissolved organic nitrogen and phosphorus are now described with four additional equations. The modification was tested at the Gulf of Finland in a numerical experiment made with plausible initial and actual boundary conditions for the years 2009—2014. Comparison of simulation with the available field observations indicates quite reasonable reproducibility of seasonal and inter-annual variations of spatial distribution of hydrophysical and biogeochemical characteristics, including almost a perfect match between simulated and observed dynamic of organic nutrients. The most important distinction from natural prototypes is the overestimated total amounts of inorganic nitrogen and phosphorus, which can be caused by the deficiencies in   the prescription of initial and boundary conditions as well as in the current parameterizations of pathways and rates of mineralization fluxes. The finer tuning of SPBEM-2 requires more extensive sensitivity analysis.

The thermobaric regime of hydrate-bearing sediments is investigated in this paper by solution of the phase transition problem gas hydrate — gas + water when both linear and metallic cylindrical heat source is switched on. It is shown that the use of a needle probe in situ is strongly limited in the seas of the usual (most common) type with a bottom water temperature of about 3 °C for the study of gas hydrates accumulations on the sea bottom. Such a use is possible there only in case of very high linear source power. It was determined that only at the bottom of «warm» seas the use of a needle probe can allow not only to detect the presence of gas hydrates in bottom sediments, but also to evaluate the properties of these sediments by the nature of the temporal variations of both temperature and pressure on the surface of the probe. Since the characteristics of time changes of gas pressure near the probe are generally more differentiated than similar temperature dependencies, a high-precision pressure sensor must also be built into the probe designed for in situ use in hydrate-bearing bottom sediments. The obtained solution of the phase transition problem can serve as a basis for the process of the experimental data interpretation.

The paper presents estimates of the characteristics of non-stationarity of the field of flow around an ellipsoid of rotation, obtained as a result of numerical experiments with a three-dimensional non-hydrostatic model of the system “water – air”. The evolution of the structure of internal wave disturbances (in the temperature field), propagating from the ellipsoid of rotation with an elongation of 1:6, streamlined by a stream of a stratified medium with a constant velocity, was studied. Significant non-stationarity of the flow field has been identified. When flow around, wave disturbances of a complex structure are formed, the studies of which were carried out using wavelet analysis of time series at points in the vicinity of the ellipsoid and constructing integral wavelet spectra for water temperature across and along the region. In the first case, based on the comparison of the wavelet spectrum at each chosen time and integral over the entire period, a significant variability of the spectral characteristics of the water temperature field in time was demonstrated. Considering the temporal evolution of spatial integral wavelet spectra for water temperature across and along the region, the alternation of groups of wave disturbances with energy flows from small (vortex) scales to large and vice versa is clearly seen. In some periods, there is a complete destruction of the space-time pattern of perturbations. The group structure and its dynamics appear more clearly in the transverse plane above the ellipsoid.

In 2015—2016, comprehensive research was conducted on the underwater plume observed from outer space near Sevastopol in the area of the deep-water runoff. In ship expeditions vertical hydrological profiles, current velocity profiles and optical characteristics of water were obtained on the grid of stations, and water samples were taken for chemical and microbiological analysis. In-situ studies were accompanied by surveys from various satellites. It is reliably shown that the plume is a layer of turbid water, stretched along the coast for a distance of several kilometers and localized at the depth of the pycnocline. Plume can be observed from Space in the visible range when the pycnocline rises up to the sea surface. An analysis of the data indicates that the existence of the plume is a consequence of emergency state of the underwater pipe of the wastewater discharge system, which is confirmed by the results of satellite image analysis. An estimate of location of the probable break of pipeline is obtained. In the area of the source of pollution, detachment of the pieces of turbid waters from the main layer and their lifting to the sea surface was revealed. Chemical composition of turbid waters corresponds to the sewage one. The existence of a plume near the coast leads to unfavorable ecological consequences, in particular, the concentration of ammonium ions in the plume region is 2 times higher than the maximum permissible level, and microbiological analyses indicates destabilization of the microbial community and destructive processes in phytoplankton caused by pollution.

Field studies of acoustic sea noises and multipath effect characteristics of signal propagation in shallow Arctic seas covered by drifting ice are carried out. The research is made for the purpose of optimization of characteristics of the equipment of a hydro-acoustic channel of digital communications determined for control and operative diagnostics of technically complex underwater objects, such as submerged buoy stations, producing oil and gas platforms and pipelines. A most modern technology of equipment construction, OFDM-type (orthogonal frequency-division multiplexing), which provides simultaneous emanation of large amounts of narrow-band carrier frequencies for parallel binary code transfer, are planned to be used on the channel of communication. Parallel code transfer with some redundancy added provides high speed of data transfer, maximum remotability and noise immunity. Basic OFDM technology is particularly targeted for multipath effect jamming protection and pulse noise jamming peculiar to shallow ice-covered seas. Statistical measures for levels and nature of sea noises and quantitative meanings of amplitude distribution and certain acoustic rays’ time delays caused by tending and drift velocity influence are received, as well as hydrological conditions. The results of the studies allow the reasonable choice and calculations of equipment parameters with OFDM technology, and they also allow providing reception of specified performance characteristics in adverse hydrological conditions.

The paper presents new materials on the creation of digital maps of vertical and horizontal anomalies of the magnetic field of the spreading zones in the World Ocean. The results of the calculations are presented in the form of maps of the anomalies of vertical and horizontal components of the induction vector of the Earth’s magnetic field for the water area of the World Ocean. The task of identifying marine magnetic linear anomalies is considered not only from modular data, but also taking into account the advantages that the specificity of the appearance of the anomalies of the horizontal and vertical components can give. Component anomalies for the World Ocean are calculated using the SPbF IZMIRAN component model of the Earth’s magnetic field. On the example of the mid-oceanic ridge in the North Atlantic, the appearance of alternating strip magnetic anomalies of the horizontal and vertical components is shown. Based on the study of changes in the structure of anomalies of vertical and horizontal component of the Earth’s magnetic field and their intensity with height, an assessment was made of the effectiveness and information content of landmarks for the purposes of air navigation in the spreading zone. The components of magnetic anomalies presented in this paper may  be of interest for the theory of plate tectonics, the specification of the age of the ocean lithosphere, and the mode of formation of the ocean floor due to the spatial and temporal movement of tectonic plates. The specificity of the structure of magnetic anomalies of the spreading zones increases the importance of the parameters of the navigation informativity of the anomalies of the vertical and horizontal components of the magnetic field. This expands the possibilities of their use in autonomous correlation-extremal sea and air magnetic navigation in the difficult conditions of the waters of the ocean basins.