Specific Features of the Propagation of Tsunamis in the Northwest Part of the Black Sea

We perform the numerical analysis of the propagation of tsunamis in the Black Sea from the zones of seismic generation located to the south of the Crimea and in the northwest part of the sea. It is shown that the tsunamis induced by earthquakes in the Crimean seismic zone are entrapped by the nearest part of the shelf and do not result in noticeable oscillations of level in the northwest part of the sea. This enables us to explain the absence of manifestations of tsunamis in 1927, 1939, and 1966 near Odessa. The tsunami waves generated by earthquakes in the northwest part of the sea are characterized by the directivity of their propagation. The wave height is maximum in the areas corresponding to the north and east directions of propagation. Hence, the north coast of the sea and the Kalamit Bay (Crimean Peninsula) are characterized by elevated tsunami hazard for earthquakes occurring in the northwest part of the Black Sea. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 46–53, November–December, 2005.     

Simulation of the Evolution of Wave Fields Induced by a Moving Cyclone over the Northwest Shelf of the Black Sea

The wave fields generated by cyclonic atmospheric disturbances in the region of the northwest shelf of the Black Sea are studied by using a σ-coordinate model. The problem is solved in the hydrostatic approximation with regard for nonlinearity and turbulent viscosity. To improve the space resolution of the model, we realize the procedure of embedded grids. It is shown that the action of a cyclone results in the formation of domains of pronounced surges whose shapes and location reflect the changes in the wind situation. The vertical structure of wave currents first depends only on the location of the atmospheric disturbance over the water area but, in the course time, begins to reflect specific features of the bottom topography.__________Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 42–54, January–February, 2005.     

Field Measurements of Sea Currents on the Mangistau Shelf of the Caspian Sea

Oceanology - The pilot Kazakhstan–Russia project provided the first systematic data in a long time on coastal currents in one of the least studied areas of the Caspian Sea, namely the...     

Experiment of Wind Wave Parameter Research on the Black Sea Shelf

The article presents information on the current experiment of research on wind wave parameters in the Black Sea coastal zone. Two wave-meter devices are the part of the measuring equipment of the Black Sea testing site Gelendzhik of the Shirshov Institute of Oceanology (IO RAS). The integral characteristics of wind waves accumulated and obtained in real time may be in demand by experts in operational and satellite oceanography.

     

Investigation of Transformations of the Local Regions of Pollution in the Northwest Part of the Black Sea Caused by the Motion of a Cyclone

By the method of mathematical simulation, we study the evolution of local discharges of pollutants on the northwest shelf of the Black Sea induced by the motion of a cyclone. We use the nonlinear equations of motion of a homogeneous viscous fluid in the hydrostatic approximation and the equation of turbulent diffusion. A cyclonic formation is represented by a moving axisymmetric area of low pressures. The discharges of pollutants are caused by the action of instantaneous sources located on the sea surface. We perform the analysis of dependences of the paths of motion of polluted regions, the periods of their dissipation, and the depths of penetration of pollutants on the bottom topography and the intensity of diffusion processes. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 17–27, November–December, 2005.     

Specific features of the vertical distribution of elements of the main biogenic cycles in waters of the Northwest shelf of the Black Sea

We study specific features of the vertical distribution of elements of the main biogenic cycle in the upper layers of waters on the northwest shelf of the Black Sea in spring and autumn and the correlation between the specific features of the vertical distributions of hydrochemical and hydrological characteristics. It is shown that the location of the halocline always specifies the location of the chemocline, whereas the effect of the thermocline on the distribution of hydrochemical characteristics is ambiguous. The vertical distribution of the hydrochemical parameters can be homogeneous in the presence of the seasonal thermocline. At the same time, in its absence, one may observe significant vertical gradients in the distributions of hydrochemical characteristics inside the upper mixed layer.     

Manifestation of Specific Features of the Optical Properties of Atmospheric Aerosol over the Black Sea in the Interpretation of SeaWiFS Data

We consider the problem of quantitative evaluation of the optical characteristics of seawater according to the data of satellite measurements. The principal physical mechanisms responsible for the errors in the atmospheric correction made with the help of the standard NASA algorithm are established. It is shown that the models of atmospheric aerosol realized with the help of this algorithm are inconsistent with its actual properties over the Black Sea.     

Sulfur Isotopes in the Upper Part of the Black Sea Anoxic Zone

New data are reported on the sulfur isotope composition and concentration of sulfide and sulfate in the upper part of the Black Sea anoxic zone as a function of the potential water density. The observations were performed at a station with the coordinates 44.489° N and 37.869° E three times a week every two days. A local negative deficiency in sulfate concentration up to 1.7% related to the sulfate reduction processes was recorded. This anomaly in sulfate concentration was short-lived and did not affect the sulfur isotope composition. In the upper part of the anaerobic zone, the δ³⁴S(SO₄) value varied from 21.2 to 21.5‰, which could have occurred from mixing of water masses from the oxic zone (21.1‰) and the Bottom Convective Layer (23.0 ± 0.2‰). The sulfur isotope composition of sulfide ranged from ?40.8% at a depth of 250 m to ?39.4‰ at the upper boundary of the anoxic zone with a H₂S content of only 2.7 μM. Two models (mass balance and fractionation of sulfur isotopes using the Rayleigh equation) are considered to explain the differences in δ³⁴S(H₂S) values observed.     

黄、东海陆架海域温度垂直结构类型划分与温跃层分析

基于黄、东海陆架海域1997—1999年4个季节调查的CTD资料,采用拟阶梯函数逼近法对温度垂直剖面拟合逼近,然后按拟合均方差和跃层强度对黄、东海陆架区的温度垂直结构进行类型划分,共划分为6个类型:三层结构型(T型)、主跃层上位型(U型)、主跃层下位型(L型)、多阶梯状结构型(M型)、异常结构型(A型)和垂直均匀型(H型)。分析结果表明:温度垂直结构类型在黄海区域为:春季呈L型;夏季呈U型;秋季呈T型;冬季呈H型。东海北部春季基本呈T型;夏季西部呈T型,东部呈U型;秋、冬季演变为H型;东海南部春、夏季主要呈L型;秋、冬季除近岸出现逆温类型外,大部分区域呈H型。利用风和潮的混合卷挟模式阐述了各种温度垂直结构的形成机制,最后给出了黄、东海陆架海域的主温跃层特征值的区域分布和季节变化。     

On the Structure of Water Exchange Between the Deep Northern and Shelf Southwestern Part of the Kara Sea over the Brusilov Sill

Oceanology - During cruise 81 of the R/V Akademik Mstislav Keldysh comprehensive studies of the Kara Sea were carried out over sill separating the central spur of the St. Anna Trough and the Novaya...     

Occurrence and Distribution of Cetaceans in the Northeastern Part of the Black Sea

Oceanology - Studies of Black Sea cetaceans were carried out in September 2018 (11 days, 799 km of the survey route) and June 2019 (12 days, 1174 km of the survey route). The research vessel...     

Variability of Particulate Organic Phosphorus in the Northwestern Part of the Black Sea

Based on long-term (1985–1995) monitoring data, the paper considers the peculiarities of seasonal variability in the spatial and vertical distribution of particulate organic phosphorus (Р_POM) in the surface layer and in the photosynthetic zone in the northwestern Black Sea. Regression equations, experimental data, and satellite observations for the chlorophyll a concentration allowed us to evaluate the seasonal longterm (1979–1995) variability in Р_POM in the surface layer and photosynthesis zone. The ratios of the concentrations of particulate organic carbon, nitrogen, phosphorus, and chlorophyll a are calculated and statistical estimates of seasonal changes in the Р_POM in the areas with different degrees of influence of river runoff and water of open seas are obtained. The consistency of intra-annual changes in the concentrations of Р_POM, chlorophyll a, and phytoplankton biomass is shown, which indicates the role of phytoplankton in the formation of Р_POM and in its intra- and interannual variability in the northwestern part of the sea. It is shown that long-term seasonal variations in Р_POM and related changes in the concentration of chlorophyll a depend on the variability of bulk river runoff, the extent of its abundance in the northwestern shelf, and regional hydrometeorological conditions.     

东海陆架冰后期潮流沙脊地貌与内部结构特征

东海陆架以宽平的地形、充分的陆源沉积物供应、快速沉降和强动力场为特征，中外陆架发育大规模潮流沙脊地貌。潮流沙脊走向大致为NW—SE向分布，与区域潮流主方向一致或成较小交角。东海陆架冰后期潮流沙脊以不对称横剖面为特征，陡坡倾向SW。沙脊内部发育典型的高角度前积斜层理，倾向与沙脊横剖面陡坡方向一致。这些斜层理可以划分为高达4组不同特征的组合，分别代表潮流沙脊发育的不同阶段，对应于冰后期海平面上升的不同时期。东海陆架潮流沙脊主体形成于冰后期海侵阶段，目前仍然受到陆架潮流场的影响，沙脊顶部为再沉积活动层。     

Examples of Approaches to Studying the Temperature Variability of Black Sea Shelf Waters with a Cluster of Temperature Sensor Chains

Oceanology - The article describes a technique for studying the spatiotemporal variability of the temperature of the water medium in the Black Sea shelf zone using a cluster of anchored temperature...     

Structure of Phytocenoses of the Yenisei Estuary and Adjacent Kara Sea Shelf in Late Spring

Oceanology - The research is based on the materials collected during cruise 66 of R/V Akademik Mstislav Keldysh in the Yenisei estuary and over the adjacent Kara Sea shelf in the latitudinal range...     

Transport and fate of Danube Delta terrestrial organic matter in the Northwest Black Sea mixing zone

Within the framework of the European project EROS 21, a biogeochemical study of particles transported from the Danube Delta to the Northwestern Black Sea whose carbon cycle is dominated by riverine inputs was carried out in spring off the Sulina branch of the Danube Delta. The distribution of particulate organic carbon (POC), chlorophyll a (Chl a), C/N, and δ¹³C evidenced an omnipresent contribution of terrestrial organic matter throughout the study area together with a dilution of these inputs by freshwater and marine organisms. Four lipid series, n-alkanoic acids, n-alkanes, n-alkanols, and sterols were analyzed by gas chromatography and gas chromatography/mass spectrometry. Several signature compounds were selected to delineate dispersion of terrestrial organic carbon: (1) long-chain n-alkanoic acids in the range C₂₄–C₃₄, long-chain n-alkanes in the range C₂₅–C₃₅, long-chain n-alkanols in the range C₂₂–C₃₀, 24-ethylcholesta-5,22-dien-3β-ol (29Δ^5,22) and 24-ethylcholesterol (29Δ⁵) for vascular plant-derived material and (2) coprostanol (27Δ^0,5β) for faecal contamination associated with sewage effluents. A marked decrease was observed between the concentrations of different vascular plant markers characterizing the two end members: riverine at salinity 0.3 and marine at salinity 15.5. The decrease observed for marine/riverine end members (expressed as a function of organic carbon) varied in a large range, from 4% for n-alkanes to 18.6%, 20.4% and 24% for n-fatty acids, n-alkanols and sterols, respectively. These values reflect a combination of various processes: size-selective particle sedimentation, resuspension of different particle pools of different sizes and ages, and/or selective biological utilization. The multi-marker approach also suggested the liberation in the mixing zone of terrestrial moieties, tightly trapped in macromolecular structures of the riverine material. The greatest decrease for marine/riverine end members was observed for coprostanol (0.9%), underlining the efficiency of the mixing zone as a sink for sewage-derived carbon.     

Spatial Structure and Recurrence of Large-Scale Temperature Anomalies of the Sea Surface Temperature in the Black Sea

Composites of warm and cold temperature anomalies were constructed, and the distribution of the recurrence frequency of days with temperature anomalies in the four seasons of the year was evaluated based on satellite measurements data on sea surface temperature. Regions of the formation of cold anomalies in the northwestern part of the sea and warm anomalies in the northern and northeastern parts of sea were distinguished, related to advection by the Black Sea Rim Current. The distribution functions of temperature anomalies and the lifetime of the cold and warm anomalies were estimated. A plausible physical mechanism of the generation of cold anomaly in the southeastern marginal part of the sea related to Ekman pumping of cold water from the thermocline was considered.     

日本九州西北部第三纪含煤盆地与东海陆架盆地的地层对比

日本九州五岛列岛周围有许多早第三纪含煤沉积小盆地 ,它们正处于东海盆地的东北端 ,又处于东海与日本海的对马盆地相衔接的部位 ,研究它们是很有意义的。最近日本帝国石油株式会社的岩田尊夫等人就发表了两篇文章 ,谈及这些盆地的划分、地层层序、沉积过程以及孢子—花粉组合和地层对比。在日本九州西北部 ,西北—东南向和东北—西南向的两组断层甚为发育 ,它们控制着下第三系含煤盆地的平面几何形态 (多为长斜方形 )。在五岛列岛西北方有福江盆地 ,它是东海陆架盆地的东北延伸部分。在五岛列岛以南也发育了 5个下第三系沉积小盆地 ,其中五…     

Horizontal and Vertical Structure of Geostrophic Currents in the Black Sea According to the Data of the Summer Survey Performed as a Part of the ComSBlack-92 Program

We describe the methodology and software developed for the numerical analysis of the characteristics of the horizontal and vertical structure of geostrophic currents. We present the results of computation of these characteristics according to the data of the summer survey of the Black Sea carried out as a part of the ComSBlack-92 program. The distinctive features of the space structure of geostrophic currents discovered as a result and the established parameters of their variability may supplement the existing data on the current field in the Black Sea.     

Influence of vertical motions on maintaining the nitrate balance in the Black Sea based on numerical simulation

The upwelling of deep water associated with the influence of cyclonic wind curl and the difference in the buoyancy of the inflows in the lower and upper water layers is observed in the central part of the Black Sea. The resulting vertical water motions contribute to the transport of ammonium to the upper boundary of the anaerobic zone. In the suboxic zone, ammonium is converted to nitrate via nitrite as a result of the nitrification, and thus it can supply the nitrocline in the water basin. Within the framework of this paper we discuss the effectiveness of this mechanism on the basis of the numerical simulation. The calculations were performed using a one-dimensional physical-biogeochemical model for the upper 600-m sea water layer, which takes into account seasonal variations in atmospheric parameters and vertical motions. The model describes the biological and redox processes in the suboxic zone. We have estimated the contribution of different constituents into the balance of nitrogen compounds in the euphotic water layer. It is shown that ammonium nitrogen coming from the deep water due to vertical water motion plays a significant role in maintaining the balance of nitrates in the central part of the Black Sea.