共查询到20条相似文献，搜索用时 406 毫秒
1.
O. V. Krivenko 《Physical Oceanography》2006,16(6):337-349
Based on the experimental data obtained in 1990–1993 by the method of isotopic tracers with the help of a stable isotope of
nitrogen (15N), we establish basic regularities of the formation of “new” and regeneration production in the Black Sea and reveal the
factors specifying their combination. It is shown that the rates of nitrate and ammonium uptake by microplankton vary from
the minimum values in winter to the maximum values in summer. In the surface layer, the uptake of nitrates corresponding to
the amount of “new” production in deep-water layers is equal to ∼ 50% (in winter) and ∼ 30% (in summer) of the total uptake
of inorganic nitrogen compounds by microplankton. In the zone of photosynthesis, the average fractions of nitrates are equal
to 31 ± 10% in winter and 41 ± 10% in summer. The minimum values of this parameter are attained in the middle of spring and
in autumn. The fraction of “new” production (f-ratio) and the integral content of nitrates in the zone of photosynthesis are connected by a hyperbolic dependence. The period
of cyclic transformations of nitrates in this zone decreases from several dozens of days at the beginning of winter to 12
h in the mid-spring. In summer, this period is equal, on the average, to one day. The average period of cyclic transformations
of ammonium is equal to 15 ± 4 h in winter and 5 ± 3 h in summer.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 29–43, November–December, 2006. 相似文献
2.
We construct a one-dimensional nonstationary isopycnic model of vertical exchange in the Black Sea with regard for the processes
of draining and transformation of waters of the Sea of Marmara (or “plume”), vertical diffusion, and the action of winter
convection in the upper layer. It is assumed that mixing in the basin is local in space and time and that the winter wind
action remains constant from year to year in the analyzed version of the model. The temperature of the upper mixed layer introduced
to simulate the winter conditions is regarded as the principal external variable factor. Within the framework of the accepted
restrictions, the model enables us to study the annual and interannual variability of the thermohaline characteristics and
hydrochemical parameters in the water column of the sea. As an example, we perform the numerical analysis of the periodic
action of external thermal conditions on the characteristics of the system with a period of six years.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 3–21, September–October, 2006. 相似文献
3.
Yu. I. Sorokin 《Oceanology》2011,51(6):969-977
The rate of the hydrogen sulfide oxidation in the redox zone of the Black Sea and the rate of the hydrogen sulfide formation
due to bacterial sulfate reduction in the upper layer of the anaerobic waters were measured during the period of February–April
1991. The measurements were made using a sulfur radioisotope under conditions close to those in situ. It was established that
the hydrogen sulfide is oxidized in the layer where oxygen and hydrogen sulfide coexist, which is under the upper boundary
of the hydrogen sulfide layer. The maximum rate of the hydrogen sulfide oxidation was recorded within the limits of the density
values δτ of 16.20–16.30, while varying in the layer from 2 to 4.5 μM/day. The average rate of the hydrogen sulfide oxidation
was 1.5–3 times higher than that during the warm season. Sulfide formation was not observed at most of the stations in the
examined lower portion of the pycnocline layer (140 to 400 m depths). Noticeable sulfate reduction was detected only at one
station on the northwestern shelf. A probable reason for such noticeable changes in the sulfur dynamics in the water mass
of the Black Sea may be the intensified hydrodynamics in the upper layers of the water mass during the cold season. The data
suggesting that hydrogen sulfide oxidation proceeds under the hydrogen sulfide boundary indicate the absence of the so called
“suboxic zone” in this basin. 相似文献
4.
Identification of local upwelling zones in the Bering Sea using hydrochemical parameters 总被引：1，自引：0，他引：1
Based on the data for the oxygen in the surface layer of the Bering Sea, the areas of pronounced undersaturation (down to
75–80% and below) were distinguished in the surface layer of the Bering Sea. The low percentage values as such of the oxygen
saturation might be sustained at the sites of quasi-stationary upwellings. However, in this case, the surface layer should
be characterized by decreased temperature and increased salinity as related to the surrounding waters, as well as by increased
concentrations of nutrients (phosphates, nitrates, and silicon). The corresponding tests showed that most of the distinguished
“patches” of oxygen undersaturation were verified by the oceanological parameters; i.e., these were local upwellings. Some
of them were studied quite thoroughly (even with the mechanisms proposed for the formation of steady water lifting), particularly
in the area of the Aleutian Islands. However, there are some poorly studied areas (so-called questionable ones) at which the
low oxygen content is not confirmed by the hydrochemical parameters (plainly, they are not available); this requires more
profound and detailed study. 相似文献
5.
We perform the experimental verification of the applicability of the theory of similarity to the wave boundary layer and the
assessment of wave-induced perturbations of the air flow depending on various conditions of stratification of the atmosphere
and the state of the sea. The measurements were carried out from a stationary platform located in the coastal part of the
Black Sea. The experimental procedure is based on the simultaneous measurements of the profile and fluctuations of the wind
speed at 5–6 levels in the 1.3–21-m layer, the elevations of the sea surface, the directions of waves and winds, and the mean
gradients of temperature and humidity of air. The structure of the boundary layer in the region of measurements depends on
the direction of the wind. For weak and moderate onshore winds (< 9 m/sec), the approximate balance is preserved between the
production and dissipation of turbulent energy in the cases of unstable and neutral stratification. On the average, the estimates
of friction velocity according to the profiles are higher than the dissipative estimates by 10% mainly due to the deficiency
of dissipation near the surface. For the offshore wind, the structure of the boundary layer abruptly changes and is determined
not by the local parameters but by strong turbulent eddies formed over the dry land. The intensity of low-frequency turbulent
fluctuations and the gradient of wind velocity near the surface in the coastal zone are 1.5–2 times higher than for the open
sea.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 42–61, May–June, 2007. 相似文献
6.
O. A. Yunev 《Oceanology》2011,51(4):616-625
Using the data of daily primary production, as well as intraannual and long-term changes in the concentration of chlorophyll
“a” and hydrochemical characteristics, the annual primary production of phytoplankton in the deep-water part of the Black
Sea is estimated for the three key periods in the contemporary evolution of the sea: preeutrophication, very intense eutrophication,
and the present-day period characterized by deeutrophication. It is shown that eutrophication in the second part of the 20th
Century led to an increase in the production level not only in the shelf of the Black Sea, but also its deep-water areas.
By the end of the 1980s and the early 1990s, the value of the annual primary production in this part of the sea increased
from 63 ± 18 g C m−2 yr−1 (in the 1960s) up to 135 ± 30 g C m−2 yr−1. On the contrary, after 1993, mainly because of reduced runoff of biogenic substances into the Black Sea from land based
sources, there was a decrease in the annual production of phytoplankton in the deep-water areas of the sea, which is currently
about 105 g C m−2 yr−1. 相似文献
7.
N. B. Shapiro 《Physical Oceanography》2000,10(6):513-531
We discuss the results of numerical experiments carried out within the framework of a new version of the quasiisopycnic model
of the Black Sea [1, 2]. We take into account the stochasticity of the wind stress, vertical shift of the flow velocity in
the upper quasihomogeneous layer, and diapycnic mixing. We generalize the procedure of “convective adjustment,” which enables
us to consider the propagation and transformation of waters of the Sea of Marmara. It is shown that the consideration of these
factors enables one to determine the structure and seasonal variability of hydrothermodynamic fields in the sea more correctly.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
8.
G. K. Korotaev 《Physical Oceanography》2005,15(2):71-78
It is generally accepted that the stationary wind circulation in the lower layer of a two-layer sea is negligibly weak even
if the bottom topography is taken into account. This opinion is true for the oceanic scales where the bottom topography has
no global slope along the meridian. However, in the case of circulation in closed and semiclosed seas, the trenchlike structure
of the bottom topography together with the beta-effect can significantly affect the intensity of currents in the bottom layer
of the sea. In the present work, we use a simple model to consider an example of intensification of deep-water wind-induced
circulation under the influence of the meridional slope of the bottom. The discovered effect enables us, in particular, to
make an assumption that the deep-water circulation in the Black Sea is much more intense than it was supposed earlier.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 3–10, March–April, 2005. 相似文献
9.
The temperature minimum layer, called “dichothermal water”, is a characteristic feature of the North Pacific subarctic gyre.
In particular, dichothermal water having a density of approximately 26.6 sigma-theta (σθ), which corresponds to the densest water outcropping in winter in the North Pacific, is seen in the Bering Sea. In order
to clarify the water properties, and the area in which and the process by which the dichothermal water is formed, a new seasonal
mean gridded climatological dataset with a fine resolution for the Bering Sea and adjacent seas has been prepared using historically
accumulated hydrographic data. Although the waters of the Alaskan Stream have temperature minimum layers, their temperature
inversions are very weak in climatologies and the core densities of the temperature minimum layers are much lighter than 26.6σθ. On the other hand, in the Bering Sea one can see the robust structure of temperature minimum layers, the core density of
the dichothermal water being around 26.6σθ. In addition, it has been found that the properties of the dichothermal water observed in the warming season are almost the
same as those in the winter mixed layer. That is, the dichothermal waters are formed in the winter mixed layer in the Bering
Sea. Since these waters are found in the Kamchatka Strait, i.e., the main exit of the Bering Sea waters, it can be supposed
that the dichothermal waters are exported from the Bering Sea to the Pacific Ocean by the Kamchatka Current.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
G. S. Karabashev 《Oceanology》2011,51(1):36-38
Based on the comparative analysis of the characteristics of the early summer maxima of the normalized radiance from the satellite
ocean color data, the seasonal trend of the concentration of the chlorophyll “a,” and the species composition of the phytoplankton
from determinations in water samples from the Black Sea, it is concluded that the summer chlorophyll maximum is due to the
coccolithophorid bloom occurring from late May to mid June in the Black Sea basin. 相似文献
11.
On the basis of a simple stationary linear model and a contemporary nonlinear model, we study the mesoscale characteristics
of the fields of vertical velocity and vorticity of winds over the Black Sea. It is shown that, in the idealized case (without
taking into account the coastal features), the temperature contrast between the land and the sea in both models leads to the
formation of circulation cells in the coastal zone. However, the mountainous features prove to be the main factor affecting
the process of circulation for the actual synoptic situations. We present the map of monthly average vorticity of the surface
winds constructed according to the nonlinear mesoscale model with a resolution of 30 km for January 1996–2001.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 52–61, January–February, 2005. 相似文献
12.
The effects of a week-long exposure to copper sulfate (0.05–5000 mg/l) and cadmium chloride (2 and 10 mg/l) upon the morpho-functional
characteristics of the Black Sea bivalve mollusks Anadara cf. inaequivalvis and Chamelea gallina were studied. The changes in the morpho-functional state of mollusks at the impact of these metals are distinguished. These
changes included a 60% decrease in the hemocytes’ concentration in the hemolymph and a 5- to 7-fold decline of the hemocyte
adenosine triphosphate (ATP) content, along with the appearance in the mollusks of “brown” cells and lipofuscin-like pigment.
The exposure to both metals caused similar changes. 相似文献
13.
Based on the scatterometer QuickScat wind data and the water-leaving radiances from the ocean color scanner SeaWiFS data for
2000–2004, we composed a pair of mean annual images of a testing site in the South Caspian Sea under conditions of west-bound
and east-bound winds corresponding to the offset and onset state of the shallows in the east of the testing site. It was established
that both the “offset” and “onset” radiances grow shorewards, but the former becomes about twice as large as the latter in
the middle of the shallows with 10–15 m of water, while their difference tends to zero at the seaward and coastal boundaries
of the shallow. These and other findings are hypothetically attributable to the inclination of the sea floor of the shallows,
due to which the surfacing of bottom sediments resuspended by the drift current takes less time under the “offset” wind conditions
than under the “onset” ones. The study’s results indicate that the effect of the bottom sediments resuspension upon the structure
of the images of the marine shallows is universal in character and needs to be taken into account to improve the bio-optical
algorithms for estimating the admixtures in the thickness of the shallows from the satellite data. 相似文献
14.
E. N. Badyukova 《Oceanology》2010,50(6):953-960
On the basis of geologic-geomorphologic studies, an alternative concept regarding the evolution of the Northern Caspian Sea
Region and the adjacent areas in the boundary of the Pleistocene-Holocene is presented. A supposition is made about the existence
of a large lagoon in the North Caspian Region that the Volga River emptied into forming a delta. Later, water from the lagoon
flowed as a “stratum” stream into the Black Sea through the Manych Strait. A conclusion is reached that the Baer mounds were
formed on the bottom of this stream. 相似文献
15.
16.
An improved method of two-dimensional kinematical structural analysis of tides (the “method of the orbits”) is presented.
This method allows us to determine the parameters of the primary tidal waves shaping the observed tidal structure. The construction
of the vertical orbits for the individual tidal harmonics is performed along the horizontal coordinate axes; one of them is
oriented along the so-called “reactive azimuth,” which coincides with the direction of the tidal current at the instant of
the zero tidal level. In this case, the orbit parameters include information on the amplitude-phase relations of the interfering
waves and allow us to determine the angle of the waves crossing. The suggested method enables us to quantitatively describe
the mechanism of the tidal formation with oblique interference both close to the shore and in the open sea. We tested the
new method in two local zones of the White Sea (Morzhovets Island and in the vicinity of the entrance to Kandalaksha Gulf)
where the presence of rotating semidiurnal tidal currents evidences the significant role of oblique interference of tidal
waves. In these zones, the developed method made it possible to perform a detailed quantitative analysis of the local tide
structure caused by the M2 tidal wave, which plays the dominant role in the White Sea. The result describes the structure of the propagation of the
primary tidal waves better than the field of “pure” energy fluxes that was used earlier. 相似文献
17.
A. S. Samodurov V. Z. Dykman V. A. Barabash O. I. Efremov A. G. Zubov O. I. Pavlenko A. M. Chukharev 《Physical Oceanography》2005,15(5):311-322
We describe a new measuring complex aimed at the investigation of small-scale processes in the upper active layer of the sea.
The necessity of creation of a complex of this sort is justified and a circle of problems that can be solved with the help
of this complex is described. The scales of resolution of horizontal and vertical inhomogeneities in measuring in the mode
of vertical probing are theoretically estimated. The basic technical characteristics of the complex are presented. We also
present the results of laboratory and field tests, which confirm the agreement between the calculated and actual technical
possibilities of the complex. The structural features of various versions of the “Sigma-1” measuring complex (the “Sigma-1P”
point-to-point-operation version and the “Sigma-1Z” probing version) are described.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 60–71, September–October, 2005. 相似文献
18.
S. I. Pogosyan A. M. Durgaryan I. V. Konyukhov O. B. Chivkunova M. N. Merzlyak 《Oceanology》2009,49(6):866-871
A device for integrating cavity absorption measurements (ICAM) with an internal diameter of 80 mm suitable for field research
is described. The spectral features of the light absorption by some cyanobacteria, green algae, and diatoms in the integrating
sphere were studied and the dependences of the absorption on the cell concentration were determined in comparison with the
conventional measurements in a 1-cm cuvette. The sensitivity of the chlorophyll estimation with the ICAM reached 0.2–0.5 mg
m−3. The results of the ICAM application for the direct analysis of the natural phytoplankton and dissolved organic (“yellow“)
matter in the Black Sea and the Sea of Japan are described. 相似文献
19.
E. B. Shibanov 《Physical Oceanography》2005,15(3):192-202
We study the problem of the choice of initial approximation for the reflection and transmission coefficients in numerical
methods based on the principle of “interaction.” The disadvantages of the approximation of single scattering are demonstrated
and the regularities of propagation of light in media with strongly anisotropic scattering are analyzed. Semianalytic expressions
proposed for the evaluation of the initial approximation enable one to determine the characteristics of the light field in
plane-parallel media with relative errors of about 10−5 within the framework of the algorithm of “adding” of layers.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 62–72, May–June, 2005. 相似文献
20.
We provide an expert quality assessment of the data for 1932–1993 and used these data to perform the numerical analysis of
the carbonate system of the aerobic zone in the Black Sea. The intraannual and long-term variations of the carbonate system
are studied in the abyssal part of the sea for 1960–1993. We propose explanations of the intraannual variations of the analyzed
system for various layers of the aerobic zone and reveal long-term variations of the pH values, total alkalinity, and the
ratios of the components of the carbonate system. We discover and explain the observed increase in the concentrations of TCO2 and CO2 and the partial pressure of carbon dioxide pCO2, as well as a decrease in pH values and the concentration of CO32− in waters of the aerobic zone of the Black Sea. 相似文献