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1.
The article deals with deposits exposed in sections along the rivers of the Caspian lowland and on the eastern slope of the Ergenei. The conclusion is made about the lagoonal origin of chocolate clays lying on high-capacity subaerial and alluvial–deltaic deposits. The impact of the Caspian Sea level rise on coastal processes is examined. Taking into account the regularities in the behavior of the coastal zone during sea level rise, subaerial deposits with such thickness in the outcrops could not have been preserved during the early Khvalynian transgression from –100 m. Another curve of Caspian Sea level fluctuations is proposed, where there is no deep Atelian regression between the Khazarian and Khvalynian transgressions. It is concluded that the Khazarian transgression was one of the largest in the history of the Caspian Sea. Its level was slightly less than that of the Khvalynian transgression. The rise of the level of the latter began not from –100 m, but from about 5–15 m; i.e., this transgression was in fact an oscillation of the Caspian Sea against its gradual regression after the Khazarian transgression. Sea level oscillations contributed to the formation of lagoonal-transgressive terraces, in which chocolate clays accumulated.
相似文献2.
Long-term hourly data from 12 tide gauge stations were used to examine the character of tidal oscillations in the Caspian Sea. Diurnal and semidiurnal tidal peaks are well-defined in sea level spectra in the Middle and South Caspian basins. High-resolution spectral analysis revealed that the diurnal sea level oscillations in the Middle Caspian Basin have a gravitational origin, while those in the South Caspian Basin are mainly caused by radiational effects: the amplitude of diurnal radiational harmonic S1 is much higher than those of gravitational harmonics О1, P1, and K1. In the North Caspian Basin, there are no gravitational tides and only weak radiational tides are observed. A semidiurnal type of tide is predominant in the Middle and South Caspian basins. Harmonic analysis of the tides for individual annual series with subsequent vector averaging over the entire observational period was applied to estimate the mean amplitudes and phases of major tidal constituents. The amplitude of the M2 harmonic reaches 5.4 cm in the South Caspian Basin (at Aladga). A maximum tidal range of 21 cm was found at the Aladga station in the southeastern part of the Caspian Sea, whereas the tidal range in the western part of the South Caspian Basin varies from 5 to 10 cm. 相似文献
3.
A. A. Svitoch 《Oceanology》2007,47(2):282-289
This paper presents a reconsideration of the hypothesis that the Khvalynian transgression of the Caspian Sea resulted from an abundant inflow of meltwaters from Siberian proglacial lakes through the Aral Sea and via the Uzboi channel and may be considered as a prototype of Noah’s Flood. A thorough analysis of the evidence suggested by the proponents of this hypothesis revealed a lack of factual substantiation; there are no facts indicating the existence of the Aral flow-through lake or of the Siberian proglacial water supply to the Caspian Sea. The spatial distribution of the mollusk fauna provides no support for the view that the Khvalynian transgression was essentially influenced by thawing of ice sheets on the Russian Plain. The Khvalynian transgression, though geologically short-term, could not be an analogue of Noah’s catastrophic flood. The sea level rose at a rate of a few centimeters per year for a few thousand years; this interval covered the lifetimes of many generations of the Caspian coast inhabitants. The Khvalynian water overflowing via the Manych Strait into the Pontian basin provided an even smaller influence. It resulted in flooding of the middle part of the Black Sea shelf, in a 30-m sea level rise, and in a water salinity increase by 5‰. 相似文献
4.
Yu. A. Karpychev 《Oceanology》2007,47(6):857-864
The structure of the bottom sediments in Kara Bogaz Gol Bay is correlated with the history of the sea level fluctuations in the Caspian Sea during the Novocaspian time based on the radiocarbon geochronology of the coastal and bottom sediments. Instrumental observations of the sea level and the hydrochemical regime of the bay are considered to substantiate the correlations obtained. 相似文献
5.
In this work, the history of the development of the Turali area (the Dagestan coast of the Caspian Sea) in the Late Holocene
is under consideration. The analysis of the geological structure of the bay bar that separates the Bolshoy Turali lagoon from
the sea, the granulometric analysis of the coastal deposits, and the data of geo-radar profiles make it possible to assert
that the large eolian relief forms were formed during the New Caspian (Novokaspiyskoe) transgression of the Caspian Sea. 相似文献
6.
A. A. Svitoch 《Oceanology》2012,52(4):526-539
During the Pleistocene regressive epochs, the Caspian Sea shelf became entirely (the Atel and Mangyshlak regressions) or partly (the Cheleken and Enotaevka regressions) exposed, which was accompanied by a change in the relief formation and sedimentation settings in the drained areas. The adjacent offshore areas were subjected to the transformation of the seawater salt composition, the temperature regime, and the biotic communities. The sea level falls during the Caspian Sea regressions were accompanied by large-scale environmental changes: the desiccation of spacious sea bottom areas, transformations of the landscapes and the relief formation and sedimentation settings, alterations of the seawater??s salt composition in the offshore areas, and the transformation of the biotic communities. The largest regressions were characteristic of the Tyurkyan, Bakuan-Khazarian, Khazarian-Khvalynian (Atel), and post-Khvalynian epochs. The shelf became entirely exposed (234 000 km2) during the maximal Atel and Mangyshlak regressions. During the Cheleken and Enotaevka regressions, the shelf was half drained. The epochs when the Caspian shelf was entirely exposed were marked by different climatic events in the Caspian Sea region and the adjacent glacier-affected areas of the Russian Plain. In general, the main regressive epochs correspond to interglacials on the Russian Plain, although this correlation was much more complex. 相似文献
7.
Correlations between the changes in the climate of the Caspian Sea region and in its level and the variations in the North Atlantic climate are studied. The indices of North Atlantic oscillation (NAO), Atlantic multidecadal oscillation (AMO), the intensity of Atlantic thermohaline circulation (ATHC), and the air humidity above the North Atlantic are used as basic indicators of climatic variations that influence the Caspian Sea. Results of an experiment for reproducing the World Ocean circulation and the parameterization of cyclic climate peculiarities made it possible to reveal their impact on the formation of Eurasian climatic variability and on the level regime of the Caspian Sea. This impact is studied through the variability of ATHC, the NAO index, and a composite index of moisture transport (CIMT) that is proposed as a result of the studies. 相似文献
8.
Preliminary studies of Caspian Sea have shown the possibility of gas hydrate accumulations, because of suitable physicochemical conditions, existence of clayey deposits, and high concentrations of organic matter. Studies have indicated that gas hydrates are mainly composed of methane. Therefore, based on physicochemical equations for methane hydrate stability in different pressure, temperature, and salinity, this study was designed to calculate the potential of gas hydrate formation in the Caspian Sea basin. For this, data of more than 600 locations were analyzed and in each location, upper and lower limits of methane hydrate formation zone were calculated. Then, the zoning maps of upper and lower limits were prepared which can be useful for exploring the gas hydrate as an energy source or predicting gas hydrate hazards. According to the calculations and maps, methane hydrate formation in Caspian Sea, theoretically, can take place from near the seabed to 4000 and 2500 m beneath the sea surface when low and high geothermal gradient are supposed, respectively. By comparing the results with gas hydrate zones revealed in geophysical profiles, it has been shown that, in Caspian Sea, gas hydrates probably accumulate near the lower limit when a high geothermal gradient is assumed. 相似文献
9.
The main objective of this study is the simulation of flow dynamics in the deep parts of the Caspian Sea, in which the southern and middle deep regions are surrounded by considerable areas of shallow zones. To simulate spatio-temporal wind induced hydrodynamics in deep waters, a conjunctive numerical model consisting of a 2D depth average model and a 3D pseudo compressible model is proposed. The 2D model is applied to determine time dependent free surface oscillations as well as the surface velocity patterns and is conjunct to the 3D flow solver for computing three-dimensional velocity and pressure fields which coverage to steady state for the top boundary condition. The modified 2D and 3D sets of equations are conjunct considering interface shear stresses. Both sets of 2D and 3D equations are solved on unstructured triangular and tetrahedral meshes using the Galerkin Finite Volume Method. The conjunctive model is utilized to investigate the deep currents affected by wind, Coriolis forces and the river inflow conditions of the Caspian Sea. In this study, the simulation of flow field due to major winds as well as transient winds in the Caspian Sea during a period of 6 hours in the winter season has been conducted and the numerical results for water surface level are then compared to the 2D numerical results. 相似文献
10.
The mineral composition of heavy and light subfractions of the modern bottom sediments of the Caspian Sea is studied. The concentration of the minerals in the Caspian Sea made it possible to identify nine terrigeneous mineralogical provinces in its area. Based on the mineral composition of the heavy subfraction of the bottom sediments, the main sources of the fragmentary material supply are established. The distribution of the terrigeneous minerals over the bottom area in the modern bottom sediments of the Caspian Sea depends on the sources of the fragmentary material; the stability and flotation properties of minerals; the morphology of the bottom; and the hydrodynamic conditions. 相似文献
11.
By the data of the surveys performed in 1976, 1983, and annually from 1995 to 2006, the successive transformations of the
ecosystem were traced in the Central and Southern Caspian Sea: from the anoxic conditions in 1933–1934 to the oxic state during
the low level period in 1978, then the hypoxia increase and accumulation of nutrients registered anew after 1995, and to the
hydrogen sulfide appearance in the near-bottom layers of the Southern Caspian Sea. Some irreversible changes in the silicon
distribution in the Central Caspian Sea were revealed (the concentration increase to 217 μM at the depth of 780 m, which considerably
exceeded the absolute values for the World Ocean). 相似文献
12.
Martin Ekman 《Marine Geodesy》2013,36(3):161-168
The mean sea level along the coasts of the Skagerrak, the Kattegat, and the Danish Straits—i.e., the transition area between the North Sea and the Baltic Sea—has been computed geodetically. The basis consists of mean sea level data from Denmark, Norway, and Sweden in various more or less inappropriate height systems. These are transformed and unified into a common height system relevant for oceanographic purposes to show the deviation of the mean sea level (1960) from the mean geoid, with Normaal Amsterdams Peil (NAP) as zero. The geodetically determined mean sea surface is compared with oceanographic model results for parts of the area. Among other findings, the outflow of low‐salinity water from the Baltic Sea, as well as its separation from high‐salinity North Sea water along the Kattegat‐Skagerrak front are clearly revealed. 相似文献
13.
Sea level changes in the Baltic Sea are dominated by internal, short-term variations that are mostly caused by the ephemeral nature of atmospheric conditions over the Baltic area. Tides are small and their influence decreases from western parts of the Baltic Sea to the Baltic Proper. Superimposed to the large short-term sea level changes (up to few decimeters from day to day) are seasonal and interannual variations (centimeters to decimeters). This study focuses on the comparison of sea surface heights obtained from observations and from a high resolution oceanographic model of the Baltic Sea. From this comparison, the accuracy of the modeled sea surface variations is evaluated, which is a necessary precondition for the further use of the oceanographic model in geodetic applications. The model reproduces all observed Baltic sea level variations very reliably with an accuracy of 5 to 9 cm (rms) for short-term variations (up to 2 months) and 8 cm (rms) for long-term variations (>2 months). An additional improvement of the model can be attained by including long-period sea level variations of the North Sea. The model performs well also in the case of extreme sea level events, as is shown for a major storm surge that occurred at the southern coast of the Baltic Sea in November 1995. 相似文献
14.
The paper presents the results of applying a new polarization method proposed in [28] to identify the type of surface pollution and differentiate between mineral oil films (crude oil and its emulsion and petroleum products) and films of other origin in sea surface radar images. The method is based on calculation of the quantitative characteristics for the ratios of suppression or intensification of scattered radio signals of different physical nature, viz., caused by capillary ripples several centimeters long, or wave breaking. TerraSAR-X satellite coaxial-polarized (VV/HH) SAR images are used. The data for analysis have been collected in areas where spots and slicks of known origin regularly occur, such as oil spills and natural oil seeps in the Gulf of Mexico and the Caspian Sea, and biogenic films in the Caspian Sea. The results of analyzing radar images from the TerraSAR-X satellite with controlled experimental oil emulsion spills in the North Sea are used for comparison. Based on the analysis of ten TerraSAR-X radar polarization images with surface sensing angles greater than 30°, it is shown that this method makes it possible to distinguish between oil spills and slicks formed by natural oil seeps and biogenic films with an accuracy higher than 80% regardless of the observation area. 相似文献
15.
Izvestiya, Atmospheric and Oceanic Physics - The Caspian Sea water dynamics on the boundary of its northern and central basins is considered. A high-resolution numerical model (with a grid... 相似文献
16.
使用ROMS(regional oceanic modeling system)模式模拟了40年的渤黄东海温盐流,数据包括三维的温度、盐度、流速、流向和海表高度,同时包含了逐小时的潮汐信息。将模拟结果与观测资料和卫星反演数据进行对比,检验了模式准确性。整体上,模式模拟的水位与近岸观测值基本一致,能够准确再现风产生的增水;模式较为准确的再现了渤黄东海的温度分布,在深水区模拟的温盐剖面与观测值基本一致;模式模拟渤黄东海区域的海表高度和海表流与卫星反演结果相比偏小,但分布趋势相近。模式结果可以为研究气候变化对水位的影响和黄海暖舌的扩散过程等现象提供数据支持。 相似文献
17.
Variability in water temperature, salinity and density was investigated based on field measurements near Anzali Port, in the
Southern Caspian Sea in 2008. Seasonal changes of seawater properties were mainly observed through the upper 100 m layer,
while below this layer seasonal variations of the parameters were minor. Vertical structure of the temperature in the southern
coastal waters of the Caspian Sea is characterized by a significant seasonal thermocline between 20–50 m depths with vertical
variation in temperature about 16°C in midsummer (August). Decrease of the thermocline occurs with the general cooling of
the air and sea surface water, and deepening of the mixed layer during late of autumn and winter. Seasonal averages of the
salinity were estimated in a range of 12.27–12.37 PSU. The structure of thermocline and pycnocline indicated agreement between
changes of temperature and density of seawater. Seasonal pycnocline was observed in position of the thermocline layer. 相似文献
18.
The present study investigated the variability of monthly mean sea level data and discussed its relation with climatic events in the Red Sea during 1958–2001. The data were obtained from Simple Ocean Data Assimilation (SODA), for three different locations (north, central and south) in the Red Sea. Spatial and temporal variability as well as trends and periodicity of sea level time series records in the three locations was investigated using One-way ANOVA test, weighted running mean filter and autocorrelation spectral analysis. Results revealed that mean sea level in the northern Red Sea was permanently lower than its central and southern parts. Moreover, the mean sea level during winter and spring in the three locations was significantly higher than summer and autumn seasons. Increasing and decreasing of sea level trends with respect to time were also observed. Inter-decadal variations in sea level including a fairly regular quasi 2.5–2.7 year oscillation in all seasons were detected, although its amplitude varied among different cycles. Studying the cyclicity in the hydroclimatic record can resolve some of the complexities of the hydroclimate system. The sign of Quasi Biennial Oscillation, El Niño Southern Oscillation and sunspots events may have an important influence in sea level variations of the Red Sea. 相似文献
19.
渤黄海沿海2月份海平面异常偏高成因分析 总被引：5，自引：0，他引：5
使用1980—2010年的水位、气温、海温、气压和风场资料,对中国渤黄海沿海2月份的海平面变化特征以及异常偏高成因进行了探讨,分析结果表明:近30年,渤黄海沿海2月份海平面呈现明显的上升趋势,2009年和2010年2月份的海平面达到近30年的高值,冬季高海平面导致全年平均海平面偏高。近两年2月份海平面处于多个长周期振动的高位重合期,各振幅叠加的结果近100 mm,对海平面起了明显的抬升作用。高海平面使得辽宁、河北以及山东等沿岸地区的海水入侵距离和土壤盐渍化程度均有所增加,海岸侵蚀加重;上海在2009—2010年连续2年2月份发生了近年较严重的咸潮入侵。2009年和2010年2月份,气压较常年同期显著偏低,冬季季风显著偏弱,是海平面上升的主要原因之一。 相似文献
20.
2012年中国沿海海平面上升显著成因分析 总被引：3，自引：0，他引：3
2012年,中国沿海海平面变化最突出的特点是海平面升高显著。海平面总体比常年高122mm,较2011年偏高53mm,达1980年以来最高位。本文使用中国沿海及西北太平洋区域近30a的水位、海温、气温、气压和风等水文气象资料,详细分析了中国沿海海平面2012年异常偏高的成因。结果表明:2010-2012年中国沿海海平面处于2~3a、8~9a和准19a周期震荡的高位,几个周期震荡高位叠加,对海平面上升起了明显的影响;2012年,沿海气温和海温分别较常年偏高0.4℃和0.3℃,气压较常年低1.2hPa,气压达历史最低位;2012年,中国南海夏季风爆发时间较常年偏早,结束较常年偏晚,季风持续时间较常年偏长,导致2012年5-6月和8月,在黄海和东海海域,东北风持续偏强,南海海域南风偏强,风场的异常导致黄海、东海和南海沿海海水长时间堆积,是造成海平面升高的原因之一;2012年,热带气旋登陆时间集中,影响范围广,北上和影响东北地区的台风数量均为历史之最,特别是2012年8月,有6个热带气旋相继影响我国沿海,对当月海平面升高影响明显;另外,2012年副热带高压偏北、偏东、偏弱的特点对东海和南海的海平面上升也有一定影响。 相似文献