Simulation of wind currents in Sevastopol bays

We the discuss the results of modelling wind currents in the system of Sevastopol bays. Numerical calculations are carried out according to the model of Felzenbaum. It is shown that the decisive role in the formation of distinctive features of circulation of waters and the essentially three-dimenstional character of currents in this part of the sea is played by the bottom topography and the direction of winds. These distinctive features are demonstrated for the cases where the motion is induced by the northeast and northwest winds. In the Sevastopol bays, we discovered the existence of jet longshore currents, vortex character of integral circulation, and intense processes of upwelling and downwelling. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Polarography of the bottom sediments in the Sevastopol Bay

By the method of polarographic profiling performed with the help of an Au-Hg glass microelectrode, we obtained the first high-resolution vertical profiles of the distributions of oxygen, sulfides, oxidized and reduced forms of iron, reduced manganese, and iron monosulfide in pore waters of the bottom sediments in the Sevastopol Bay. It is shown that the regional features of the vertical distributions of the main polarographically active compounds are determined by the combination of several factors: the contents of organic carbon and iron and the sizes of particles of the sediments.     

Silicon in waters of the Sevastopol Bay in spring 2008

On the basis of field studies executed in May 2008, we performed the analysis of the distribution of silicon in waters of the Sevastopol Bay under conditions of the formation of a seasonal thermocline. We discuss differences in the distributions of silicon in the surface and bottom layers, including the zone of mixing of river and sea waters. We noticed a significant difference in values of the coefficients of correlation between the concentration of silicon and the salinity for the surface and bottom layers. For bottom layer, we obtain large values of the coefficients of correlation between the concentration of silicon and other hydrochemical characteristics which are explained by the influence of the processes of transformation of organic substance.     

Methane in the Sevastopol coastal area, Black Sea

Concentrations of dissolved methane in seawater and bottom sediments, as well as of methane emanating from gas seeps were measured at 18 stations including several small bays in the Sevastopol coastal area (Black Sea) during 2007–2008. Methane concentrations in surface waters ranged from 10 to 2,970 nmol l^?1, and correlated well with values recorded for sediments. Methane concentrations in the water column were influenced by water depth, as well as by air and water temperatures. In the spring and summer of 2008, in situ CH₄ saturation relative to air was in the range of 970–71,900%. Maximum saturation was in summer. CH₄ fluxes to the atmosphere from the Sevastopol coastal area were estimated to vary from 190 to 1,550 μmol m^?2 day^?1. Gas bubbles escaping from the seepages contained about 57 vol% methane. Radiocarbon dating of the methane revealed an age not exceeding 150 years, implying a biogenic origin.     

Investigation of the influence of wind action upon the currents and propagation of impurities in the azov sea

The surge phenomena and currents in the Azov Sea caused by variable winds in the presence of stationary currents are studied by using a three-dimensional nonlinear mathematical model. The specific features of the transformations of impurities in the water area of the Azov Sea under the joint action of stationary and nonstationary winds are investigated. On the basis of the results of numerical calculations, we make conclusions concerning the dependence of the period of dissipation of impurities on the wind velocity and the location of the regions with impurities. It is shown that the variable wind significantly increases the deviations of the sea level and the area of distribution of the impurity as compared with the action solely of the stationary currents.     

Sources of Coastal Water Pollution near Sevastopol

Oceanology - The article presents findings of recent ecological investigations into marine waters in Sevastopol region and overviews the main sources of water pollution in Sevastopol Bay and other...     

Modelling of the passive turning of a turret moored vessel in conditions of compact ice

The concept of the offshore oil and gas field development using floating ship-shaped platforms, frequently named floating production units (FPU further), with turret mooring is widely used in the world, including regions with harsh environment. The direct transfer of this concept to the Arctic seas is not possible, mostly due to the difficulties of maintaining a weathervaning, or passive turning regime in heavy ice conditions. The main danger relates to the fact that the expected FPU rotation under the action of high ice loads can be accompanied by a translational displacement of the FPU away from the mooring point. As a result, the mooring system may reach an overloaded state until the FPU turns to a favourable position relative to the ice drift direction. In the paper, we are focused on the investigation of a mathematical model of the passive FPU turning on a spot under the assumption that the ice cover is described by a rigid-plastic continuum. The study is performed both analytically and by numerical simulations. A number of specific FPU motion patterns are analytically derived from the model in quasi-static approximation in the form of successive limit states of the system FPU – ice continuum. Some results of the corresponding numerical simulation are presented that confirm the existence of similar solutions in the full dynamic setting of the problem. A partial parametric analysis of the problem is also performed.     

Reconstruction of the space and time variability of thermohaline fields in the Sevastopol Bay

The aim of the present work is to reconstruct the space and time variability of the three-dimensional fields of currents, temperature, salinity, and density in the Sevastopol Bay under the influence of the actual external factors in 1999. For this purpose, we use a version of the numerical multilayer model on the σ-coordinates. A vast array of the data of observations accumulated as a result of regular monitoring of the Sevastopol Bay contains, in particular, the data on the sea-surface temperature measured with six-hour intervals (at the hydrometeorological station located near the center of the bay) and almost monthly vertical profiles of temperature and salinity obtained at seven hydrological stations. The comparison of the numerical results with the data of observations enables us to conclude that, in general, the model fairly correctly describes the space structure and rearrangements of the fields of temperature and salinity. Among the most important distinctions, we can mention the fact that the fresh river water penetrating into the bay is mixed with seawater faster than predicted by the model. We also discuss the causes of these distinctions. Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 23–39, September–October, 2008.     

海湾分类系统研究

在全国海湾调查的基础上,将《中国海湾志》所记载的96个海湾的基本要素进行了统计分析,选择了海湾的水域率、开敞度、形态系数、动力参数等量化指标,对中国海湾分类进行定量化划分的探索,同时对海湾的成因分类也进行了有益的探讨.     

Propagation of passive impurities in the northwest part of the Black Sea under the action of cyclones moving to the north

We perform the theoretical analysis of the turbulent diffusion of impurities in the sea in the presence of long waves. The role of generators of long-wave motions is played by moving cyclonic baric formations. At the initial time, the zone of pollution is specified in the form of a spot of a passive substance localized near the Karkinitskii Bay in the Black Sea. The results of our investigations enable us to estimate the contribution of long waves to the process of diffusion of the spot of impurity depending on the trajectory of motion of the cyclonic formation. It is shown that, under the action of waves induced by the cyclone, the maximum concentration in the spot decreases more rapidly only for a certain period of time. Moreover, we observe a northwest displacement of the spot specified by the structure of the wave field.Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 3–18, July–August, 2004.     

Modelling the influence of currents on wave propagation at the entrance of the Tagus estuary

A study of the wave propagation and of the consequences of the influence of currents on waves in the Tagus estuary is performed in the present work. For this purpose a high-resolution SWAN domain was coupled to a wave prediction system based on the two state of the art phase averaged wave models, WAM for wave generation and SWAN for nearshore wave transformation. The most important factors affecting the incoming waves are the local currents and the wind. These influences were evaluated by performing SWAN simulations in the target area with and respectively without considering the tide level and tide induced currents. The model results were compared with wave measurements, validating in this way the results of the wave prediction system developed herewith.     

Oxygen and Sulfides in Bottom Sediments of the Coastal Sevastopol Region of Crimea

Spatial variations in the distribution and fluxes of dissolved oxygen and sulfide in bottom sediments of Omega and Sevastopol bays have been studied. The results of analysis reveal that the distribution of dissolved oxygen and sulfide in pore water depends mostly on seasonal variations in the oxygen concentration in bottom water, grain size, the organic carbon content in bottom sediments, and, additionally for Sevastopol Bay, the iron content. The oxygen flux at the bottom of Sevastopol Bay is 20 times larger in winter–spring compared to that of Omega Bay. Anaerobic conditions in Sevastopol Bay sediments are observed much closer to the surface, with their subsequent development in bottom water.     

Seasonal Dynamics of Microbial Processes in Bottom Sediments of the Sevastopol Coastal Area

Oceanology - A seasonal study of microbial methane oxidation (MO) and sulfate reduction (SR) processes in bottom sediments was carried out at five stations in the estuarian Sevastopol coastal area,...     

Seiches in bays forming a coupled system

The seiches occurring in two adjacent bays, Koaziro Bay and Moroiso Bay, situated in Miura Peninsula at the mouth of Tokyo Bay, are very regular, and the phenomenon of beat appears in their amplitudes of oscillation. Nakano once presented a theoretical explanation of this phenomenon, considering two rectangular bays of the same size and form as well as of uniform depth, by assuming that a kind of coupling takes place between the two bays through a portion of water flowing across the mouth of each bay. In the present paper, the validity of the theory has been proved in a series of hydraulic model experiments. The experiments have shown that, in the case of the two adjacent rectangular bays mentioned above, there are two distinct modes of oscillation viz. (i) the co-phasic oscillation and (ii) the contra-phasic oscillation, and since the frequencies of these oscillations are close to each other, when they come to interfere, the beat phenomenon occurs.It has also been found that, when a tsunami wave enters the two bays, the mode of oscillation of the seiches occurring in them changes in the following manner: the co-phasic oscillation the oscillation accompanied with the beat phenomenon the contra-phasic oscillation. As regards this phenomenon, the authors have presented a possible explanation by considering the dissipation of energy due to wave scattering.     

Quantitative distribution of the starfish in some bays of the far east

The quantitative distribution of the starfish was analyzed in Vostok Bay, Nakhodka Bay, and Kievka Bay (the Sea of Japan). Nine species were found. Three species of Asteroidea dominated (Asterina pectinifera, Asterias amurensis, and Leptasterias sp.). The population density of A. pectinifera and A. amurensis was higher in the shallow waters compared to the sublittoral zone. The frequency of the occurrence, the biomass, and the population density of Leptasterias sp. were the highest for the shallow waters and decreased accordingly when the water temperature decline on the transect from Vostok Bay to Kievka Bay. In Kievka Bay, which was characterized by the lowest water temperatures, Leptasterias sp. dominated in the littoral and sublittoral zones followed by A. pectinifera and A. amurensis.     

Regularities of seasonal variations in the content and distribution of oxygen in waters of the Sevastopol Bay

We study the regularities of annual variations in the concentration of oxygen and the degree of saturation of waters in the Sevastopol Bay with oxygen in 1998–2009. The three-dimensional specific features of seasonal variations in the distribution of oxygen in waters of the Sevastopol Bay are revealed. Two periods can be separated in the annual course of the content of oxygen in the surface layers of waters in all parts of the bay: the period of supersaturation in March–September and the period of undersaturation in October–February. In the bottom layer of waters in all parts of the bay, we observe the undersaturation of waters with oxygen for the whole year.     

Tidal oscillations in shallow bays and sediment movement

The present study seeks to understand the interaction of a directly forced, large amplitude, tidal mode with non-directly forced resonant or nearly resonant tidal modes in a coastal bay or basin despite frictional effects. It is shown that in shallow basins a non-directly forced resonant mode may be indirectly activated with a response that may be time dependent, with the amplitude of this mode increasing and then decreasing before increasing again in a cyclical manner associated with amplitude beats. A laboratory experiment and theoretical arguments are used to support these conclusions and to study the effect when the amplitude of the tidal disturbances is comparable to the depth of the basin. It is noted that the presence of such modes, whether directly or indirectly forced, and whether resonant or non-resonant, may be able to move sediment and thereby change the resonance behaviour of the basin by changing its geometry. The changes in the geometry may then change the resonant frequencies of the basin, possibly causing the decay of the mode that caused the sediment motion. The implications of the mechanism for the modelling of the tidal behaviour in other bays with more complicated geometry are considered.     

福建省主要港湾沉积物中硫化物的分布

海水养殖业在带来巨大的经济效益的同时，也给近岸海湾带来环境污染．目前．海上太多的网箱养鱼，阻碍了海水流动，使得水流减弱，残饵和鱼的排泄物沉积于海底，造成底质恶化，硫化物严重超标．     

Some results of calculation bays amplification coefficients

The coefficients of bay amplification are investigated within the limits of the linear theory of long waves by analytical and analytical and numerical methods for periodic and solitary waves.     

Modelling of the propagation and transformation of riverine waters over the north-western shelf and in the abyssal part of the Black Sea

To study the propagation and transformation of riverine waters in the framework of a multilayer model based on primitive equations, the method of through counting is suggested, involving two types of grids, namely, a fine grid in the north-western shelf area and a large-sized grid in the deep sea. It has been shown that, in the absence of wind, riverine waters propagate over the shelf and along the western coast of the sea. North-easterly wind presses this flow against the shore, thus intensifying it; as a result of this, brackish waters turn out to be nearly entirely driven from the north-western shelf area and concentrate in the western section of the open sea where they form a layer that is quasi-homogeneous, in terms of salinity. Due to the forcing of the north-westerly wind, riverine waters penetrate into the interior of the shelf area and then move southward toward the open sea, mixing up with the upwelling abyssal saltier waters and forming a tongue of relatively brackish waters in the central part of the western half-basin. Translated by Vladimir A. Puchkin.