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1.
This paper presents the first study of mapping of the Curie point depth (CPD) from magnetic data for the Black Sea and a comparison with a classical thermal modeling from heat flow data. The provided relationship between radially averaged power spectrum of the magnetic anomalies and the depths to the magnetic sources of the Black Sea vary from 22 to 36 km. Deepening of CPDs observed in the western and eastern Black Sea basins correspond with the thickest sediment areas, whereas the shallow CPDs are related to the Mid-Black Sea Ridge and thin sediment areas at the costal side of the Black Sea. For comparison, the temperature field was also modeled from heat flow data from the Black Sea along three approximately north–south directed profiles corresponding to known DSS soundings. The Curie isotherm along the profiles occurs at depths of 22–35 km. A comparison of the results of the two independent methods reveals only 8–10 % discrepancy. This discrepancy is equal to an accuracy of temperature determination from heat flow data.  相似文献   

2.
A reanalysis of atmospheric circulation in the Black Sea region is performed with a high spatial resolution of 25 × 25 km for the period from 1958 to 2001. Climatic wind speed fields are estimated, as are their spatial structure and seasonal variability. Mesoscale regions of cyclonic and anticyclonic speed vorticity, which are connected with edge effects and orography, are distinguished. To single out the monsoon mechanism in the annual votricity cycle, numerical experiments on the sensitivity that the regional atmospheric circulation has to the sea-surface temperature perturbations have been carried out. Large-scale regional peculiarities of the surface wind field are considered for different seasons. The vorticity of the surface wind speed and strength is assessed. Large annual average values of the vorticity are obtained which are comparable with the range of seasonal variability; they evidence the defining role that wind plays in the generation and seasonal variability, as well as the average cyclonic water circulation in the Black Sea.  相似文献   

3.
Data from field observations and numerical model simulations are used to understand and quantify the pathways by which passive tracers penetrate into the Black Sea intermediate and deep layers. Chlorofluorocarbon (CFC) concentrations measured during the1988 R.V. Knorr cruise show strong decrease with increasing density in the Black Sea and illustrate the very slow rate of ventilation of deep water in this basin. We develop a 3D numerical model based on the Modular Ocean Model (MOM), and calibrate it in a way to produce consistent simulations of observed temperature, salinity and CFCs. One important feature is the implementation of a special parameterization for convection, which is an alternative of the convective adjustment in MOM and handles the penetration of the Bosporus plume into the halocline. The model forcing includes interannually variable wind, heat and water fluxes constructed from Comprehensive Ocean–Atmosphere Data Set and ECMWF atmospheric analysis data and river runoff data. The analysis of observations and simulated data are focused on correlations between thermohaline and tracer fields, dynamic control of ventilation, and the relative contributions of sources at the sea surface and outflow from the Bosporus Strait in the formation of intermediate and deep waters. A simple theory is developed which incorporates the outflow from the strait along with the vertical circulation (vertical turbulent mixing and Ekman upwelling) and reveals their mutual adjustment. The analyses of simulated and observed CFCs demonstrate that most of the CFC penetrating the deep layers has its source at the sea surface within the Black Sea rather than from the Marmara Sea via the Bosporus undercurrent. Under present-day conditions, the surface CFC signals have reached only the upper halocline. Intrusions below 600 m are not simulated. The major pathways of penetration of CFCs are associated with cold-water mass formation sites, Bosporus effluent, as well as with the diapycnal mixing in the area of Rim Current. Future CFC sampling strategies coherent with the unique conditions in the Black Sea are discussed.  相似文献   

4.
Many gas seepages, temperature, pressure, salinity, anoxic environment and high source gas potential of the Black Sea indicates that the Black Sea might have huge potentials for biogenic and thermogenic gas hydrates. However, the last important parameter to consider gas hydrate as an energy source is the type of sediments. Coarse marine sands are considered as good hydrate reservoirs because of high porosity and high permeability. Only very limited data is available related to the types of lithology of the Black Sea sediments. Hence, in this study, the literature data (especially the drilling and coring data of DSDP Leg 42B program) about gas seepages, temperature gradient, pressure gradient, salinity, anoxic environment and high source gas potential, and the types of the sediments in the Black Sea were investigated and analyzed. Although gas seepages, temperature gradient, pressure gradient, salinity, anoxic environment and high source gas potential of the Black Sea are appropriate for producible gas hydrate reservoirs, the sediments of the Black Sea appear to be generally fine grained with high clay content. Sandy-silt and silty sand layers in turbidites of the Black Sea might be potential producible hydrate reservoirs but these sediments are fine. As well as turbidites, separate thin sand layers might be potential gas hydrate reservoirs as an energy source in the Black Sea.  相似文献   

5.
An analysis is given of the methods of operational oceanography based on measurements derived from satellite data, observations acquired by drifters and passing vessels, and modern simulations of marine and oceanic circulations. In addition, a historical review is conducted of the previous and current research in this field carried out in the Soviet Union, Ukraine, and Russia. A discussion is given of the principles underlying the design of an effective data-computing system (DCS) for solving the problems of operational oceanography and the implementation of the prototype system for the Black Sea within the joint research project of the Russian Academy of Sciences (RAS) and the National Academy of Sciences of Ukraine (NASU) “The Black Sea as an Ocean Simulation Model.” The effectiveness of applying the multicomponent splitting method in the construction of sea circulation models and specialized DCSs with integrated algorithms of variational assimilation of observational data is estimated. The concept of using the Black Sea as a testing site for innovations is developed. The underlying idea of the concept is the similarity of the Black Sea dynamics with processes in the oceans. The numerical Black Sea circulation models used in the project are described, their development areas are discussed, and the requirements to a Black Sea observing system are defined.  相似文献   

6.
I. Genov 《Oceanology》2009,49(4):540-557
A model for the palaeoenvironmental evolution of the Black Sea and its adjacent basins during the past 20.000 years, in which variations in sedimentation, erosion, and hydrologic processes as a result of climatic change are taken into consideration, is developed. The data used include those from five cruises in the Black Sea with the participation of the author, seismo-acoustic data in the possession of the Institute of Oceanology in Varna, and data from the published literature. The most important result is that the water level of the Black Sea is controlled largely by that of the Marmara Sea via the Bosporus sill. The water circulation in the south part of the Bosporus channel as natural regulative mechanism of the Black Sea level during 11800–9000 yr C14 BP is produced. A succession of climatic and water conditions for the Black Sea by pollen analysis is presented. The linear ridges on the Black Sea shelf as result of the lower Holocene regression are proved by means of a stratigraphic interpretation of the seismo-acoustic profiles. The levels of the Black Sea, Marmara Sea, and Mediterranean at regarded intervals of time are presented. An attempt at explanation of maximum number of facts from the study region with this model is made.  相似文献   

7.
A numerical technique is presented for simulating the hydrophysical fields of the Black Sea on a variable-step grid with refinement in the area of IO RAS polygon. Model primitive equations are written in spherical coordinates with an arbitrary arrangement of poles. In order to increase the horizontal resolution of the coastal zone in the area of the IO RAS polygon in the northeastern part of the sea near Gelendzhik, one of the poles is placed at a land point (38.35° E, 44.75° N). The model horizontal resolution varies from 150 m in the area of the IO RAS polygon to 4.6 km in the southwestern part of the Black Sea. The numerical technique makes it possible to simulate a large-scale structure of Black Sea circulation as well as the meso- and submesoscale dynamics of the coastal zone. In order to compute the atmospheric forcing, the results of the regional climate model WRF with a resolution of about 10 km in space and 1 h in time are used. In order to demonstrate the technique, Black Sea hydrophysical fields for 2011–2012 and a passive tracer transport representing self-cleaning of Gelendzhik Bay in July 2012 are simulated.  相似文献   

8.
In most of the studies devoted to the analysis of the thermal regime of the Black Sea basins, the high sedimentation rate is regarded to be the principal reason for the low values of the surface heat flow as compared to the deep flow. We used the basin modeling technique for a more detailed assessment of this issue with regard to the new geological and geophysical data on the age and structure of the sedimentary cover and basement of the Black Sea basins. The use of enhanced seismic data, together with a more accurate estimation of the age limits of the sedimentary sequences in the region, allowed us to refine the results of the previous studies. Based on the calculations performed for an actual cross section with actual properties of the sedimentary rocks under compaction and the basement rocks, it is shown that any version of the sedimentation and evolution of the basin compatible with the geological and geophysical data available lead to heat flow values that are significantly greater than those actually observed. Our analysis proves that the sedimentation alone, as was implied in the previous studies, cannot explain the decrease in the deep heat flow at the floor surface down to values of about 34 mW/m2. It is shown that the temperature influence of the invasion of dense though heated waters of the Mediterranean Sea that occurred about 7000 years ago helps one to explain the low present-day heat flow values in the deep-water parts of the Western and Eastern basins of the Black Sea. The application of the basin modeling technique allowed us to pose a version of the thermal evolution of the lithosphere in the Western basin of the Black Sea compatible with the high heat flow at the end of the Cretaceous, with three stages of subsidence of the sea floor down to its present-day depths, and with the low heat flow values measured in the basin. According to the geophysical data, this version implies a relatively high-temperature present-day thermal regime in the basin’s lithosphere with a lithosphere thickness of about 60 km.  相似文献   

9.
The automatic system of operational forecasting of the Black Sea state which functions at the Marine Hydrophysical Institute is presented. Principles of the system construction are considered; the marine environment models used for forecasting, the data streams required for the system functioning, and tools for validating and visualizing the results of sea-state calculations are described. Some examples of investigating a number of processes and phenomena in the Black Sea are given.  相似文献   

10.
Active faults aligning in NW–SE direction and forming flower structures of strike-slip faults were observed in shallow seismic data from the shelf offshore of Avcılar in the northern Marmara Sea. By following the parallel drainage pattern and scarps, these faults were traced as NW–SE-directed lineaments in the morphology of the northern onshore sector of the Marmara Sea (eastern Thrace Peninsula). Right-lateral displacements in two watersheds of drainage and on the coast of the Marmara Sea and Black Sea are associated with these lineaments. This right-lateral displacement along the course of these faults suggests a new, active strike-slip fault zone located at the NW extension of the northern boundary fault of the ?ınarcık Basin in the Marmara Sea. This new fault zone is interpreted as the NW extension of the northern branch of the North Anatolian Fault Zone (NAFZ), extending from the ?ınarcık Basin of the Marmara Sea to the Black Sea coast of the Thrace Peninsula, and passing through B üy ük ?ekmece and K ü ? ük ?ekmece lagoons. These data suggest that the rupture of the 17 August 1999 earthquake in the NAFZ may have extended through Avcılar. Indeed, Avcılar and İzmit, both located on the Marmara Sea coast along the rupture route, were strongly struck by the earthquake whereas the settlements between Avcılar and İzmit were much less affected. Therefore, this interpretation can explain the extraordinary damage in Avcılar, based on the newly discovered rupture of the NAFZ in the Marmara Sea. However, this suggestion needs to be confirmed by further seismological studies.  相似文献   

11.
Active faults aligning in NW–SE direction and forming flower structures of strike-slip faults were observed in shallow seismic data from the shelf offshore of Avc?lar in the northern Marmara Sea. By following the parallel drainage pattern and scarps, these faults were traced as NW–SE-directed lineaments in the morphology of the northern onshore sector of the Marmara Sea (eastern Thrace Peninsula). Right-lateral displacements in two watersheds of drainage and on the coast of the Marmara Sea and Black Sea are associated with these lineaments. This right-lateral displacement along the course of these faults suggests a new, active strike-slip fault zone located at the NW extension of the northern boundary fault of the Ç?narc?k Basin in the Marmara Sea. This new fault zone is interpreted as the NW extension of the northern branch of the North Anatolian Fault Zone (NAFZ), extending from the Ç?narc?k Basin of the Marmara Sea to the Black Sea coast of the Thrace Peninsula, and passing through B üy ük çekmece and K ü ç ük çekmece lagoons. These data suggest that the rupture of the 17 August 1999 earthquake in the NAFZ may have extended through Avc?lar. Indeed, Avc?lar and ?zmit, both located on the Marmara Sea coast along the rupture route, were strongly struck by the earthquake whereas the settlements between Avc?lar and ?zmit were much less affected. Therefore, this interpretation can explain the extraordinary damage in Avc?lar, based on the newly discovered rupture of the NAFZ in the Marmara Sea. However, this suggestion needs to be confirmed by further seismological studies.  相似文献   

12.
The formation of the fields of surface winds over the Black Sea occurs under the action of numerous physical factors. One of the most important factors is the monsoon mechanism connected with the seasonal variations of buoyancy contrasts over the sea and surrounding land. To separate the effects caused by this mechanism, we performed and described the numerical experiments aimed at the evaluation of the sensitivity of the regional model of atmospheric circulation to the variations of land–sea temperature contrasts. It is shown that the influence of these effects is restricted to the lower part of the atmosphere. The presented estimates of the climatic fields of disturbances enable us to describe the monsoon mechanism specifying the seasonal variability of the field of vorticity of the wind velocities and, as a consequence, the seasonal variability of the large-scale circulation of waters in the Black Sea.  相似文献   

13.
A numerical model of the Black Sea region (Northeastern Mediterranean) is presented in which it is regarded as a part of the mosaic plate ensemble consisting of the fixed East European platform; the active Arabian, Adriatic, and Pannonian plates; and passive East and West Black Sea and Mysian microplates, which are embedded in a plastically deformable regional orogenic matrix. The fields of displacements, stresses, and deformations in the region are calculated by means of the finite element method within the framework of a linear-viscous rheology approach to a system with nonhomogeneous viscosities. The velocity field obtained is in good agreement with published data of direct observations of plate displacements in the region. In the pressure field, areas of low pressure and decompression are established in the western part of Black Sea and in the south of the Mysian microplate. The poles of rotation of the East and West Black Sea microplates and of the Mysian microplate are computed. For the latter two microplates, significant rotational components are suggested. The East Black Sea microplate acts mostly as indenter, which transmits the collisional motion from the Arabian plate to the southern edge of the East European platform including the Crimea. According to the geodynamical model, the rates of the Cenozoic sedimentation in the Black Sea depression at the collision stage (Oligocene-Pliocene) result from the greater compression of the East Black Sea microplate as compared to the West Black Sea microplate, which, probably, experienced a kind of extension.  相似文献   

14.
Based on extensive voluminous literary data, a comparison of the Harpacticoida faunas of the Black Sea; the Sea of Azov; and the Caspian, Baltic, Barents, White, Kara, Laptev, and East Siberian seas, as well as of the Spitsbergen and Franz Josef Land areas, was performed. The degree of community and specificity of the faunas of different regions was estimated and the general patterns of the latitudinal variability in the species compositions were revealed. It is shown that the Harpacticoida faunas of geographically separated areas and even those isolated from each other such as those of the Black Sea, the Sea of Azov, and the Caspian Sea are rather similar; an hypothesis is put forward that this is caused by the common history of the seas’ formation. In contrast, the faunas of the Arctic seas (Barents, White, Kara, Laptev, and East Siberian), whose water areas are closely connected, are considerably different, being related to their different temperature conditions.  相似文献   

15.
Long-term data from 23 tide gauges were used to analyze the spectrum of mesoscale sea level variability of the Black Sea. The tides have sharp spectral peaks, and they are detected at diurnal and semidiurnal frequencies for all stations. A local wide spectral peak associated with inertial oscillations is located between the diurnal and semidiurnal tidal peaks. This peak is well known in the spectra of the current velocity variations of the Black Sea, but in the sea level spectrum it has been identified for the first time. At frequencies of >3 cpd, sea level spectra of the Black Sea have (1) wide maxima in the continuous spectrum, which correspond to the main eigenmodes of the sea with periods of 5.6, 4.8, 4.1, and 3.1 h, and (2) sharp peaks of radiational harmonics S3, S4, S5, and S6. The periods of seiches calculated in this study are close to the periods of eigenmodes of the Black Sea, obtained by the numerical modeling of other authors. The main factors influencing the formation of radiational tides in the Black Sea are presumably breezes and runoff from large rivers. The significant predominance of a harmonic with frequency of 5 cpd (S5) over other radiational harmonics is caused by the influence of an eigenmode, with a frequency of about 5 cpd. The proximity of the periods of these oscillations leads to resonant amplification and to a corresponding increase in amplitude of the radiational harmonic S5.  相似文献   

16.
A numerical primitive-equation model of the hydrodynamics of the Black Sea and the Sea of Azov in σ-coordinates is proposed. The model has a resolution of ～4 × 4 km in horizontal coordinates with 40-σ levels in the vertical and includes the four-dimensional variational initialization of temperature and salinity fields. A numerical initialization algorithm combines splitting methods and adjoint equations. Flow, temperature, sea level, and salinity fields driven by atmospheric forcing are calculated for the year 2008. The calculations are made in a variational initialization — prediction regime. Temperature and salinity fields are initialized at the end of each month. The optimality system includes forward and adjoint transport-diffusion equations for heat and salt that are linearized on the assimilation interval. Results of three numerical experiments with different sets of assimilated data in comparison with the prediction obtained from the forward model are discussed.  相似文献   

17.
It is often claimed that the Black Sea is one of the most degraded seas in the world. Management to rehabilitate the Black Sea requires cooperation between the coastal countries to be successful. However, regional cooperation in the Black Sea is poorly coordinated and lack concrete outcomes. This article analyses the performance of the Black Sea Commission in terms of enabling and fostering effective regional collaboration between the Black Sea coastal countries. The results indicate that the measures undertaken by the Black Sea Commission are effective in terms of enabling scientific and project based cooperation between the Black Sea countries. The cooperation around regional and national institutional reforms to tackle the Black Sea environmental problems is found to be weak. Despite the existing mechanisms and willingness of countries to cooperate, the implementation of the established strategic action plan for the environmental protection and rehabilitation of the Black Sea is limited. Most of the limitations of the Black Sea Commission's regime are found in its institutional and legal frameworks, which constrain the effectiveness of collaborative efforts of the Black Sea countries. To be fully functional, the collaborative governance regime of the Black Sea Commission has to be improved. Recommendations as to how these may be addressed to enhance the regime's capacity to ensure effective marine collaborative governance in the region are presented in this article.  相似文献   

18.
《Journal of Sea Research》2009,61(4):227-234
Daily observations of the sea surface temperature in the Marsdiep tidal inlet, which connects the shallow Dutch western Wadden Sea with the deeper North Sea, already started in the summer of 1860, over 140 years ago. Since the year 2000 the sampling frequency has strongly increased because of the use of electronic sensors and data logging by computer. Analysis of these temperature data has revealed variations with time scales from tidal, daily, seasonal, inter-annual, to centennial. The tidal temperature variations are generated by advection of the seasonally varying temperature gradient between Wadden Sea and North Sea, while the daily variations are mainly caused by the daily variation of solar radiation. The seasonal variation in sea surface temperature only lags a few days behind the coastal surface air temperature, contrary to the sea surface temperature in the deeper nearby North Sea, which is delayed with about 1 month. The North Atlantic Oscillation index has been used as large-scale proxy for the atmospheric forcing of the Wadden Sea temperature. Only for the winter and spring a significant correlation is found between temperature and the winter index. However, this correlation is so strong that also the annual mean temperature is correlated significantly with the North Atlantic Oscillation. At longer time scales, from decadal to centennial, also large temperature variations are observed, of the order of 1.5 °C. However, these are not related to long-term changes of the North Atlantic oscillation. These long-term temperature changes involve a cooling of about 1.5 °C in the first 30 years of the record and a similar warming in the last 25 years. In between, these long-term changes were smaller and more irregular. Similar conclusions can also be applied to individual seasons as well as to the date of the onset of spring.  相似文献   

19.
The Black Sea dynamics for two decades (1993–2012) is analyzed. The study is carried out in numerical simulation with the use of a circulation model and assimilation of satellite measurements of free surface elevations and sea-surface temperatures (SSTs). The Black Sea circulation model has a spatial resolution of 4.8 km and 35 vertical levels, which thicken toward the surface. Arrays of ERA-Interim data are used for simulating the atmospheric forcing. A set of 3D arrays of the Black Sea hydrophysical fields is calculated on a regular grid with a time resolution of 24 h. The results are analyzed and compared with available contact measurements of temperature and salinity. This comparison shows a quite good quality of the resulted hydrophysical fields of the Black Sea.  相似文献   

20.
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