Regularities of the formation of the granulometric composition of the bottom and beach deposits of the Anapa bay bar

As a result of the field studies conducted in 2010 of the spatial and temporal variability of the granulometric composition of the bottom and beach deposits of the southern part of the Anapa bay bar, the tendency of a decrease in the average size of the particles under the southward flow of the deposits of the coastal zone was revealed. The comparison of the data obtained in 1949, 1979, and 2010 shows that the average diameter of the particles in the deposits of the underwater slope also gradually decreases over the time. It was established that, with the decreasing of the particle sizes down to 0.1 mm, their nonrecoverable deposition to a depth of more than 7 m increases. Since, in the southern edge of the Anapa bay bar, over 70% of the bottom and about 60% of the beach deposits are represented by fractions smaller 0.16 mm, at this site the mass deposition of the sand material to a depth occurs. Based on the data obtained, the particle size of the sandy material recommended for the restoration of the beaches of the southern part of the Anapa bay bar was determined.     

Numerical analysis of the propagation and amplification of tsunami waves on the northwest shelf of the Black Sea

We perform the numerical analysis of the process of propagation of long waves in the northwest part of the Black Sea and consider ten possible zones of the seismic generation of tsunamis. The numerical analysis is performed on a grid with steps of 500 m. It is shown that the location of the tsunami source significantly affects the distribution of the heights of waves along the coast. As a rule, the most intense waves are formed in the closest part of the coast. The earthquakes in the South-Coast seismic zone do not lead to the formation of tsunamis in the west part of the sea. Only strong earthquakes in the northwest part of the sea can be responsible for noticeable oscillations of the Black-Sea level. The period of tsunamis near Odessa is close to 1 h and depends on the magnitude of the earthquake. In the region of Sevastopol, this period is 2--3 times smaller. In the major part of the coastal points, the extreme elevations and lowerings of the sea level do not exceed (in modulus) the initial displacements of the sea surface at the source of tsunamis. An intensification of waves emitted from the zones of generation located in the deeper part of the investigated region was observed for some parts of the Romanian coast and the west coast of Crimea. As the magnitude of the earthquake increases, the intensification of waves near the coast becomes more pronounced.     

Flocculation process of fine-grained sediments by the combined effect of salinity and humus in the Changjiang Estuary

1 IntroductionThe flocculation of fine-grained particles is onof the main reasons for the estuarine depositionWith the combination of salt water and freshwaterfine-grained particles in estuaries will experiencdrastic changes: flocculation, settlement, res…     

Model of the Baltic Sea’s dynamics with nonhydrostatic effects on a triangular grid

A numerical model of the sea’s thermohydrodynamics with a finite-difference approximation of the equations of the nonhydrostatic dynamics on a grid with a triangular form of the horizontal section of its element is formulated. The slope of the lower side of the grid’s bottom cell is determined by the given linear profile of the bottom relief. Within the shallow-water approach, the dispersion relations of the B and C grids and the developed discrete model are compared; the results of tests for different approximations of the bottom relief for a rectangular basin are given and analyzed. The developed model of the thermohaline dynamics is used for studying the influence of the nonhydrostatic effects on the circulation of the Baltic Sea and a part of Vistula Bay. The comparison of the simulation results obtained according to the version with the full equation of the vertical momentum and to that using the hydrostatic approach shows the influence of the effects of the nonhydrostatic dynamics on the structure of the simulated fields even with small horizontal resolution (the step of the grid is 3.5 km). This is manifested in the strengthening of the field of the vorticity and the increasing of the sea level gradients and the velocities of the horizontal currents, whose growth reaches 1.5 cm/s.     

南沙头通道及横沙通道对长江口深水航道的影响分析

根据长江口南沙头通道、横沙通道和南北槽分汊口的断面水深变化及长江口南北港和南北槽的分流比变化实测资料,分析了长江口北槽深水航道淤积的原因。结果表明,北槽深水航道上段淤积受多种因素影响,其中,南沙头通道和横沙通道的发展对深水航道影响最大。南沙头通道的发展在加大落潮流量的同时,对南港南岸会产生一定的冲刷,后经沙洲的阻挡,把泥沙带向南港北岸,在北槽进口段处落淤,直接影响了进入深水航道的落潮量;横沙通道由于直接贯通了北港北槽的水沙交换,因而削弱了南港和北槽之间的水沙交换,促使北槽深水航道上段产生淤积,这也是南槽河道上段刷深的一个主要原因,而南槽河道的发展必然减少了进入北槽的落潮量,进一步加剧了北槽深水航道上段的淤积。同时,科氏力与北槽南导堤分流口鱼咀工程对深水航道也造成了一定的不可忽视的影响。研究成果对治理北槽深水航道淤积问题保障深水航道正常运行具有十分重要的科学实践意义。     

The stages of the development of the basin of the Bransfield Strait

The study of the sedimentary body of the Bransfield Strait has made it possible to identify several sedimentary complexes, to construct the first electronic charts for the acoustic basement, and to establish four stages of the evolution of its floor, which updates the previous knowledge about the formation of the strait. At the first stage, there was an increase in tension stresses that were accompanied by the local splits of the continental crust at the periphery of the Antarctic Peninsula. At the second stage, a graben-like structure filled with the Lower stratigraphic complex was formed northward of the Antarctic Peninsula. At the third stage, the continuing processes of extension led to intensive explosive activity of the growing volcanic structures and filling of the graben with sediments of the Middle seismostratigraphic complex. The fourth stage, which has continued until recently, is characterized by quasi-linear localization of the major centers of volcanic activity in the band closer to the South-Shetland Islands and the formation of the Upper seismostratigraphic sedimentary complex. The evolution of the floor of the Bransfield Strait reflects the process of penetration of the American-Antarctic ridge to the continental lithosphere of the Antarctic Peninsula for the last million years.     

Generation of waves in a bounded basin by a traveling front of atmospheric pressure and the field of wind stresses induced by this front

A plane problem of generation of barotropic seiches in a bounded rotating basin by traveling atmospheric fronts is studied within the framework of the linear theory of long waves. The front is characterized by disturbances of the baric field and the corresponding field of tangential wind stresses. We deduce the modified Ackerblom formulas for the wind stresses according to the given anomalies of atmospheric pressure in which the uniform transport of disturbances of the baric field is taken into account. We perform the numerical analyses of the dependences of the amplitudes of oscillations of fluid in the basin on the parameters of the atmospheric front and the choice of the formulas for the tangential wind stresses. The influence of the wind stresses leads to significant quantitative and qualitative changes in the oscillations of fluid in the basin as compared with the case of pure baric action.     

Reconstruction of the surface temperature fields according to the fragmentary data of remote sensing

We propose a gap-filling method for the data of remote sensing of the hydrophysical and biological characteristics of the water surface. The proposed method of reconstruction is based on the representation of the fields of surface characteristics as the sums of certain numbers of empirical orthogonal functions (EOF) making the largest contributions to the total variance of the field. According to the fragmentary data obtained as a result of processing of the satellite images for the summer season, we construct estimates of the mean field and of the four-dimensional space covariance function of the surface temperature of the Black Sea. The coefficients of expansion are computed by the method of least squares or determined with the help of a genetic searching algorithm. The results of numerical experiments show that the proposed method is quite promising for applications in the problems of gap filling in the available satellite data.     

基于压磁效应的锈胀开裂混凝土梁疲劳性能试验研究

开展了5根锈胀开裂钢筋混凝土梁疲劳试验并实时记录了梁表面的钢筋压磁信号,研究锈胀开裂混凝土梁的疲劳特性和压磁信号演化规律。结果表明梁疲劳寿命随钢筋锈蚀率增大而急剧减小,梁破坏时混凝土剥落,纵筋发生疲劳断裂;磁信号时变曲线随疲劳进程不断演化,在临近疲劳破坏时曲线形态发生明显畸变,能够反映梁疲劳损伤信息;磁感应强度变化幅值的发展符合三阶段特性,在疲劳初期和破坏前增长明显;磁感应强度变化幅值对钢筋锈蚀敏感,随锈蚀率增加而增大,因此建立了疲劳作用不同阶段磁信号幅值和梁内钢筋锈蚀率的相关关系。     

Relatioship between the intensity of tsunami and the location of the epicentre of underwater earthquakes near the continental slope of the South Coast of Crimea

Within the framework of the nonlinear theory of one-dimensional long waves, we performed the numerical analysis of the dependence of the intensity of tsunami on the shelf of the South Coast of Crimea on the location of the epicentre of underwater earthquakes near the continental slope of the basin. The calculations were carried out for the parameters of the model corresponding to the Yalta tsunami of September 12, 1927. It is shown that, for the same magnitude of the earthquake, the smaller the distance from its epicentre to the coastal line, the lower tsunami waves in the coastal zone and the smaller their vertical run-up. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Peculiarities of the tectonic and magma evolution of the southwestern Indian middle-ocean crust within the range of 51°–67° eastern longitude

The comparative estimation of the parameters of the lithosphere of the Mid-Ocean Southwestern Indian range in the areas westwards and eastwards of the Atlantis II transform fault zone shows that, within this zone, an alteration in the basalt composition occurred. Eastwards of this zone, a decrease of the anomaly of the magnetic field occurred and increased average depths of the axial part (4.7 km) and thinning (up to 4–5 km) of the ocean crust with increased rates of seismic waves in the upper mantle were observed. This, first of all, indicates an anomalously cold mantle below the oceanic crust. The changes that occurred in the location of the Euler pole within the last millions of years resulted in slanting spreading in the area of the investigation with rates of opening lower than 1.8 cm/year probably accompanied by the phenomena of transtension in the active parts of the transform faults. The interaction between the Landly and Somali lithosphere plates occurred along the diffusion boundary and was accompanied by problems with tracing the chrones between the neighboring profiles of geomagnetic observations. Consequently, the more detailed investigation of the configuration of the diffusion boundary will contribute to the more accurate reconstruction of the paleogeodynamics of the central part of the Indian Ocean.     

Atmospheric Perturbations during the Flow around Mountain Groups

A nonlinear stationary two-dimensional theoretical model of the flow around the northwestern Caucasus mountains, taking the features of the real mountain terrain into account, is presented. The results of the calculations of the field of air-flow velocities and the general patterns of occurrence and the scale of the rotary-wave deformation of the air flow over the mountains are discussed. The model calculations are used to obtain the motion trajectories and fields of velocity perturbation in the troposphere for the real range of Lira scale values in the atmosphere. Based on the data, the safety indices of flights over the mountains in the Republic of Adygea are calculated for aircraft of two types: light and high-speed. The location of the major-hazard areas above the mountains and how they depend on the properties of the free-stream flow are determined. It is shown that, in certain parts of the area, this hazard can be critical.     

On several mechanisms of the formation of the compensated thermohaline inhomogeneities in the ocean

The process of the geostrophic adjustment in the stably stratified two-component medium is studied in the framework of a linear approximation. We demonstrate that, at the final stage of that process, a stationary trace is generated by the distribution of the temperature and salinity, whose horizontal inhomogeneities mutually compensate in the field of the density. The compensation level for the stationary thermohaline distributions forming during the geostrophic adjustment is estimated. The origination mechanism of compensated thermohaline inhomogeneities in hydrodynamically stable shear flows is examined. We show that, in such flows, the disturbances of the fields of buoyancy (density), pressure, and velocity damp with time, whereas the compensated disturbances of the fields of the temperature and salinity are carried off by the flow without damping. Based on the explicit solutions of the dynamic equations, it is shown that the evolution of the compensated distribution of the temperature and salinity in the shear flows usually results in the sharpening of the spatial gradients. This feature may be, among others, related to one of the factors of the origination of the fine structure of the ocean: the small-scale thermohaline inhomogeneities, which exist against the background of the smooth vertical distribution of the density.     

Influence of the monsoon climate on the distribution of neuston copepods in the Northeastern Indian ocean

The horizontal distribution of the near-surface (neuston) copepods of the family Pontellidae was studied on the meridional transects through the central part of the Indian ocean between 12°N and 12°S and in the Bay of Bengal in the summer monsoon period. Eleven species of neuston pontellids were found. The common species Labidocera detruncate and Pontellopsis villosa have the sane high frequencies in the central part of the ocean and in the Bay of Bengal. Some species are rarer in the Bay of Bengal than in the central part of the ocean. In contrast, other species are more frequent in the Bay of Bengal. The special traits of the distribution in the Bay of Bengal coincide with the lower salinity in the bay than in the central ocean. The distribution of some neritic species from the Bay of Bengal to the south is dependent on the intensification of the water translocation to the south in the summer. In the central part of the Indian Ocean, the distribution of the common neustonic pontellids is similar in the periods of the summer and winter monsoons. It is the result of the occupation of the region by the same equatorial water masses.     

Methodical aspects of the application of acoustic Doppler current profilers in the Black Sea

For the first time, an acoustic Doppler current profiler (ADCP) produced by the RDI is used in the water area of the Black Sea in the lowered mode. This direction in the application of acoustic Doppler current profilers is now in the stage of development and verification of various procedures of measurements with subsequent data processing and enables one to get the distributions of current velocities down to depths of 1000–6000 m depending on the modification of the instrument. We describe the procedures of measurements performed with the help of the ADCP in the lowered mode in the course of an expedition and the stages of processing of the primary data based on the experience of application of similar acoustic current profilers at the Marine Hydrophysical Institute of the Ukrainian National Academy of Sciences accumulated in the 1980s. We generalize the experience of application of ADCP under the hydrological conditions of the Black Sea, propose the algorithms of data processing, present the profiles of absolute current velocity at several stations, compare these profiles with the geostrophic velocities, and determine the deep-water structure of the field of currents in a shelf-open-sea section made along 31.17°E. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 31–48, July–August, 2006.     

陆地卫星相片的海岸带解译

海岸带是海洋与陆地交互作用的地带。海岸带的地貌和水文特征按潮汐海面可分为三带:高潮位以上的海滨,包括沿岸堤平原和海蚀阶地等,它们是古海洋作用的遗迹,一般不受现代海洋动力的影响,高潮位与低潮位之间的潮间带,它们随涨落潮而周期性地被淹;以及低潮位以下一直到波浪作用极限深度的水下岸坡,包括浅海和泻湖水域,属于水下环境。     

A consideration on the mechanism of generation,stagnation and disappearance of the kuroshio Meander

A mechanism of the Kuroshio Meander is discussed by comparing some observed characteristics of the Kuroshio path with short- and long-term variations of the wind field over the North Pacific. It is suggested that the meander is caused by the blocking of the Kuroshio current by the Izu-Ogasawara Ridge. The blocking occurs when the depth of the main current increases or when the vertical shear becomes weak. These structural variations are closely related to the supposed baroclinic response of the North Pacific Subtropical Gyre to long-term variations of the wind field with a period of about 56 years. The Kuroshio Meander is initiated by a trigger meander at the offiing of Shikoku Island. The trigger meander is closely related to the supposed barotropic response of the gyre to short-term variations of the wind field with a period of about 34 months.The barotropic response of the North Pacific Subtropical Gyre to the short-term variation of the wind field yields the rapid change of the vertical structure of the Kuroshio current. This change generates the trigger meander in combination with the complicated pattern of the continental slope at the offing of Shikoku Island. The trigger meander is carried away toward the Izu-Ogasawara Ridge by the Kuroshio current. When the baroclinic response of the gyre is favourable for the blocking of the main current, the trigger meander and the cold eddy grow fed by the upwelling of the deep water of the Kuroshio which is blocked at the west of the ridge. The growing stops when the scale of the trigger meander reaches to the size of the steady Rossby wave which corresponds to the over-all mean velocity of the Kuroshio at that time, because the meander exceeding the size of the steady Rossby wave moves west-ward and separates from the ridge. Then the deep water of the Kuroshio at the west of the ridge which has been under the hard constraint of the cyclonic circulation in the form of the cold eddy becomes possible to flow arround the ridge. The upwelling stops and there remains only the general dissipation process of the available potential energy in the cold eddy. Then the meander gradually decreases its size and returns to the ridge when the meander becomes smaller than the steady Rossby wave at that time. It is blocked and begins to grow there again. In this way, the Kuroshio Meander behaves as a quasi-steady Rossby wave and stagnates at the west of the ridge until the baroclinic response of the gyre becomes unfavourable for the blocking of the Kuroshio current by the ridge.     

Diagnostics of the mesoscale water exchange on the basis of statistical characteristics of the distribution of normalized radiance

A new approach is suggested for the diagnostics of manifestations of water exchange in the field of normalized radiance and automation of the analysis of digital images of the water surface. The approach is based on the application of a set of statistical characteristics of a radiance relief as an integral indication of local inhomogeneities in the water medium and provides for the estimate of these characteristics over small regions (frames) of the basin studied using multispectral information. Using the example of the SeaWiFS scanner data on the evolution of an eddy dipole in August 1998 in a study region with a size of 160 × 160 km in the northwestern part of the Black Sea, it was shown that the estimates of a number of statistical characteristics of spectrally different radiance reliefs found in the frames with a size of 40 × 40 km significantly depended on the presence of fragments of an eddy dipole or other structures in these frames. A set of such characteristics made possible reliable differentiation of radiance reliefs by the degree of randomness, by the orientation of the inhomogeneities that form the relief, and by other properties caused by the variability of the light scattering and light absorbing admixtures in the sea medium in the course of the water exchange. The approach does not require any preliminary information about the object of observations. It is promising in the basins with moderate water transparency and vertical inhomogeneity of the upper layer available for remote profiling.     

On the simulation of temperature and salinity fields in the Arctic Ocean

This paper considers the formation of the thermohaline structure of the Arctic Ocean: the formation of the salinity field and a freshwater reservoir in the Beaufort Sea and the transport of warm Atlantic water into the central part of the Arctic Ocean. A new version of the Finite Element Model of the Arctic Ocean (FEMAO) with a low spatial resolution is used. The main distinctions of this version are the following features: a new equation of state, a more sophisticated parameterization of vertical turbulence, modified formulations for the boundary conditions on open boundaries (using satellite data on the sea level) and at the upper boundary of the ocean, and the use of a variable eddy diffusivity in the parameterization of the eddy transport of a scalar. Our experiments indicated that the use of the parameterization of the eddy transport of a scalar enhances the transport of warm Atlantic waters to the central part of the Arctic Ocean through the Fram Strait; the results are most realistic when a variable coefficient is used. The Neptune effect has a contradictory role and, in the future, a higher spatial resolution should be used instead of this parameterization. We revealed that a key factor in the thermohaline fields on a large time scale is the interaction with the Atlantic Ocean, which is the source of heat and saline water.