共查询到20条相似文献，搜索用时 31 毫秒
1.
We present a survey of the principles and methods of satellite monitoring of the ocean, analyze the prospects of application of the data of satellite measurements to the operative diagnostics and prediction of circulation in the Black Sea, and discuss the physical foundations of remote sensing, the possibilities of contemporary equipment aimed at the observation of the sea surface from satellites, and the applicability of satellites as retransmitters of the data of measurements from free-drifting buoys. The contemporary oceanographic investigations carried out from satellites enable one to use the accumulated data for the numerical analysis of currents in seas and oceans in the model of general circulation as well as for the creation of a system of operative diagnostics and prediction of the state of marine environment. Examples of experimental realization of elements of the system of operative diagnostics of the state of the Black Sea based on the use of the satellite data are presented and the prospects of prediction of currents in the basin are analyzed. 相似文献
2.
We discuss the computational properties of variational algorithms of mastering the data of measurements and convergency of iterative procedures of search for an optimum distribution of the input parameters of a model and consider the model of transfer of a passive admixture. The algorithm of identification is based on the variational principles, solving the conjugate problem, and minimization of the functional of quality of a prediction. We carry out the analytic verification of the efficiency of the algorithm and discuss the problems of optimum planning of experiments from the viewpoint of conditionality of the problem of identification that is being solved. 相似文献
3.
By the method of mathematical simulation, we study the effect of changes in the width and depth of a ring-shaped basin with parabolic profile of the bottom on the space structure of waves generated by variations of atmospheric pressure periodic as a function of time. Our investigation is carried out under the assumptions of the linear theory of long waves with regard for the action of the Coriolis force. The structures of the profiles of liquid surface are compared for the cases of free and forced waves. We also establish the dependences of the period of atmospheric disturbances on the geometry of the basin for which the number of nodal points of the free-surface profile in the case of forced oscillations coincides with the number of nodal points of the profile of liquid surface in the case of free oscillations. 相似文献
4.
We analyze the possibility of existence of critical angles of incidence of sound waves along two paths of propagation of sound typical of the northwest shelf of the Black Sea from the viewpoint of the characteristics of the lower boundary of a waveguide and the space and time structure of the field of sound velocity. The lower boundary of the waveguide may possess the property of acoustic transparency both in the case of a subsurface sound channel and under the conditions of negative refraction if the bottom is formed by fine-aleurite silts responsible for significant losses in the process of propagation of sound. The angles of total internal reflection exist for bottoms formed by shell rocks under all hydrological conditions typical of this region. At the same time, for bottoms formed by fine-aleurite silts, these angles exist only for a certain vertical structure of the field of sound velocity, which enables one to use the range of angles in which the losses caused by the reflections of sound waves from the bottom can be neglected. 相似文献
5.
今年是我校建校三十周年,也是我校学报创刊三十周年,正当散布在海内外的校友与全校师生员工共庆这个光辉的海洋界节日时,作者怀着十分崇敬的心情,回顾我校首届学报主编、海洋系创始人、著名海洋教育家、中国海洋科学奠基人之一赫崇本教授的卓越功绩。 相似文献
6.
We consider a method used for the solution of the inverse problem of biooptics of the sea according to the spectrum of upwelling
radiation and propose a procedure for the correction of the data of measurement by fixing the value of reflectance at a wavelength
of 400 nm. The influence of this assumption on the results of retrieving of the concentrations of admixtures in seawater is
analyzed. The computed values of the concentration of chlorophyll correspond to the data of direct biological measurements,
and the reconstructed spectra of the absorption coefficient of phytoplankton have local maxima typical of biological particles.
The applied correction allows us to decrease the influence of measurement errors on the results of retrieving and to increase
the stability of solution of the inverse problem.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 38–50, January–February, 2008. 相似文献
7.
On the basis of the results of calculation and analysis of the characteristics of space variability of the geostrophic component of large-scale zonal currents in the tropical zone of the South Atlantic, its intrayear oscillations, and the components of tangential wind stresses, we establish the regularities of seasonal variability of the system of gradient currents on the ocean surface depending on wind conditions. We describe the specific features of seasonal meridional fluctuations of the midstreams of the geostrophic component of zonal large-scale currents and the intrayear variations of their velocity. 相似文献
8.
A. V. Ilyin 《Oceanology》2010,50(2):240-253
Due to the complex transformation of the Earth’s crust in the rift valley, the morphology of the newly formed crust is changed
by that of the province of rift mountains. The main factors of the variability of the morphological structure are as follows:
the tectonomagmatic cyclicity of the geodynamic processes at the spreading centers and the isostatic uplift of the rift valley
floor. The interchange of magmatic and tectonic cycles determines the difference in the bathymetric levels of the isostatic
equilibrium at the edges of the rift valley slopes and the beginning of the formation of the topography of the province of
rift mountains. This relief represents an indepth system of ridges and valleys rhythmically interchanging in the lateral direction.
The morphology of the province of rift mountaines becomes the morphology of the acoustic basement throughout the ocean floor,
except for the continental margins and areas of intraplate tectonics and volcanism. 相似文献
9.
M. M. Divizinyuk 《Physical Oceanography》2001,11(5):473-481
We consider the results of instrumental investigations of specific features of reverberation in the Black Sea and obtain qualitative
dependences of the duration of volume reverberation on the parameters of the Black-Sea underwater sound channel, (width, drop
of the sound velocity, and dimensions of the inhomogeneities of stratification). We also analyse the behaviour of the intensity
of surface reverberation in the far-field zone of acoustic illumination and the influence of bottom reverberation on the detection
of underwater objects.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
10.
黄河断流对黄河三角洲生态环境的影响 总被引：20，自引：1，他引：20
介绍了黄河断流的特点和原因，分析了黄河断流的变化趋势及断流在黄河三角洲地区造成的影响，指出断流不仅加重三角洲地区今后防洪的负担，而且对三角洲环境变化将产生重大影响，研究表明，黄河断流的原因是多方面的，流域降雨量的减少，水土保持减水是黄河流域水资源不足的主要原因；但人为用水如城乡工农业用水和居民生活用水量增加加剧了黄河的断流；人为引水过程中的水资源不合理利用乃至严重浪费，流域引水管理混乱，水资源统一调配的机构和机制不健全，缺乏具体有效的控制引水措施和手段是导致近年来黄河断流加剧的根源，黄河断流对三角液地区的生态环境影响是严重的而且涉及到多个方面，包括造成了三角液地区水资源的极度匮乏，影响三角洲地区水质质量，造成地下水质恶化，区域植被生态系统良性循环变差，陆区农业及海区渔业生态系统失调，湿地生态系统退化，生物多样性减少等多方面的影响。 相似文献
11.
The numerical analysis of the evolution of tsunamis is performed for the Sea of Azov. Our calculations are carried out on
a grid with steps of 500 m, as applied to seaquakes with magnitudes within the range 6–7 for 18 circular zones of generation
covering almost the entire water area of the sea. It is shown that the oscillations of the sea level in the form of cellular
waves are formed as a result of the wave reflections from the coasts. Small areas of the elevated activity of waves are formed
in the zones of irregularity of the coastline on the north coast of the sea and in the zones of shoals in the southeast part
of the basin. On the basis of the determined values of extreme elevations and lowerings of the sea level, we can make a conclusion
that the tsunami hazard is quite low for the coast of the Sea of Azov. 相似文献
12.
The inverse problem in the form of Fredholm integral equation of the first kind for determining the distribution density of
the number of specular points of 3-D Gaussian sea surface is formulated and solved. The kernel of this equation is determined
by the characteristic function of the distribution of radii of curvature at the specular points. On the basis of numerical
experiments, and also by using images of the Sun glitters it is shown that on the known distribution density of the intensity
of reflected light it is possible to define the distribution densities of both the number of specular points and the radii
of curvature at the specular points. 相似文献
13.
Numerical experiment aimed at modeling the hydrophysical fields in the sea of Marmara with regard for Bosporus and Dardanelles 总被引：1，自引：0，他引：1
We performed a long-term prognostic experiment aimed at the investigation of the process of formation of the hydrodynamic
structure of the Sea-of-Marmara waters with regard for the influence of Bosporus and Dardanelles. It is shown that the mutual
adaptation of hydrophysical fields and their adjustment to the physical and geographical conditions of the sea proceed as
a result of the action of rapid (tens of days) and slow (several tens of years) mechanisms of adaptation. An S-like jet current
directed from Bosporus to Dardanelles was formed. Two stable anticyclonic formations are well visible in the central part
of the sea. In deeper layer, an abyssal jet current was formed as a result of penetration of heavy Mediterranean waters. The
established specific features of the circulation of waters in the Sea of Marmara are confirmed by the data of observations.
We conclude that the principal features of the dynamics of waters in the Sea of Marmara are formed under the influence of
two straits.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 28–41, May–June, 2007. 相似文献
14.
Based on an analysis of the monthly average diagrams of dynamic topography, we reveal some specific features of the geostrophic circulation of waters in the South Atlantic Ocean. We present an improved picture of the structure and annual variability of the climatic large-scale circulations. They are compared with similar climatic cells of the large-scale circulation of waters in the north part of the ocean. Quantitative estimates of the characteristics of seasonal oscillations of the field of dynamic heights are obtained. 相似文献
15.
We realize the algorithm of adaptive statistics of forecasting errors for the assimilation of the climatic fields of temperature
and salinity in the σ-coordinate model of the dynamics of the Black Sea. The principal relations of this algorithm and its
simplified version based on the Kalman filter are presented. The distinctive features of realization of the algorithm specified
by the model are discussed. We also present the results of comparison of the hydrophysical fields of the Black Sea reconstructed
according to the algorithm of adaptive statistics and a simplified scheme of assimilation of the climatic data. It is shown
that the dependence of sources in the transport equations (heat and salt diffusion) on the four-dimensional variances of forecasting
errors and threedimensional measurement errors enables one to reconstruct the mutually adapted climatic parameters of the
sea more exactly. 相似文献
16.
A three-dimensional nonlinear mathematical model is used to study the dynamic processes under the action of cyclonic disturbances
in the field of stationary wind in the Sea of Azov and the specific features of transformation of the impurities. The results
of numerical calculations enable us to conclude that the maximum velocities of currents generated by a cyclone depend on the
direction of its motion. It is shown that the cyclones moving westward generate currents with higher maximum velocities than
the cyclones of other directions. It is also demonstrated that the motion of atmospheric disturbances leads to a significant
enlargement of the area of propagation of pollutants as compared with the case of action solely of stationary currents. The
influence of the velocities of stationary currents on the maximum current velocities caused by the passage of a cyclone is
also analyzed. 相似文献
17.
18.
We propose an algorithm of adaptive statistics of prognostic errors aimed at the assimilation of the climatic temperature
and salinity fields in a model of dynamics of the sea. The algorithm is used for the numerical solution of the proposed differential
equations for the dispersions of prognostic errors of temperature and salinity. The sources in the equations of advective
diffusion of heat and salt depend on the four-dimensional dispersions of prognostic errors and one-dimensional (along the
vertical coordinate) dispersions of measurement errors. The dispersions of prognostic errors are corrected at the times of
assimilation of the data. We perform the reconstruction and analysis of the climatic fields of currents in the Black Sea.
It is shown that the structure of the fields of dispersions in the upper mixed layer is determined by the vertical diffusion.
Below this layer, the distribution of dispersions depends on the vertical advection. The algorithm of adaptive statistics
of prognostic errors allows us to reconstruct the improved mutually adapted hydrophysical parameters with regard for the dynamics
of the dispersions of errors.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 26–37, January–February, 2008. 相似文献
19.
P. N. Golovin 《Oceanology》2007,47(1):42-50
Comprehensive field observations of hydrological processes in the region of the continental slope of Severnaya Zemlya in the Laptev Sea allowed us to reveal descending dense (cold) shelf water over the slope (cascading) and to determine the spatiotemporal variability of the cascading [2]. The observations represented a series of polygon surveys in the autumn-winter-spring period. The estimates of the characteristics of the slope convection of the shelf water (cascading) were based on the results of laboratory and theoretical studies of the descending of the dense water over a sloping bottom in a rotating fluid with sources of different geometry. It was shown that the cascading of dense shelf water over the continental slope mainly corresponds to a smooth (geostrophic) regime. An analysis of some thermohaline and density sections indicates, however, the possibility of the development of a wave-eddy regime of cascading and/or generation of fast gravity waves in the upper part of the continental slope. The most representative estimation of the contribution of the cascading of dense shelf water on the northern continental slope of Severnaya Zemlya to the ventilation of the intermediate waters in the Nansen Basin for five winter months is ≈0.0614 Sv. 相似文献
20.
We studied the opportunities of diagnostic of the wind roughness by distortions of Snell’s circle boundary images, i.e., images of the sky observed from underwater through a rough water surface. Models of random realization and statistically average image of Snell’s circle which takes into account various condition of illumination (overcast sky, clear sky and isotropic distribution of sky radiance) have been developed. Formulas for definition of slope variance of the sea surface by distortion of Snell’s circle boundary for one-dimensional roughness have been received. Dependence of accuracy of definition of slope variance on time of image averaging, depth of receiver diving, wind speed, range of waves forming the roughness, have been analyzed by the method of computer modeling. It has been shown on the basis of numerical calculation and experimental data that waves with length from millimeters to meters can be shown in the image of Snell’s circle depending from depth of receiver diving, receiver resolution and water turbidity. 相似文献