Vertical distribution of mesoplankton in the open area of the Black Sea

1985 ◽  
Vol 89 (1) ◽  
pp. 95-107 ◽  
Author(s):  
M. E. Vinogradov ◽  
M. V. Flint ◽  
E. A. Shushkina
Keyword(s):  
Vertical Distribution ◽  
Black Sea ◽  
The Black Sea ◽  
Open Area

scholarly journals Seasonal and Vertical Variability of Currents Energy in the Sub-Mesoscale Range on the Black Sea Shelf and in Its Central Part

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
O. S. Puzina ◽  
A. A. Kubryakov ◽  
A. I. Mizyuk ◽  
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◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Water Transport ◽  
Black Sea ◽  
Mixed Layer ◽  
Seasonal Variability ◽  
Baroclinic Instability ◽  
The Black Sea ◽  
Mesoscale Currents ◽  
Vertical Variability

Purpose. The study is aimed at investigating seasonal variability and vertical distribution of the sub-mesoscale currents energy (scales L = 1 … 10 km, T = 1 … 10 days) in the deep and shelf zones of the Black Sea. Methods and Results. The study is based on the spectral analysis of the results obtained from the NEMO model numerical calculations performed with high spatial resolution 1 km. The analysis shows that the seasonal variability of the submesoscale energy is significantly different in deep and shelf zones of the basin. At the same time, in both regions, seasonal variation of energy of the sub-mesoscale currents with scales L < 10 rm (Esp) is in good agreement with that of the density fluctuations on the same scales. In the central part of the sea, the high values of Esp are concentrated in the upper mixed layer throughout the whole year. The Esp peak is observed in winter at the depths 0–40 m, which indicates the important role of baroclinic instability induced by the inhomogeneous distribution of the mixed layer depth (MLD) in the generation of sub-mesoscale processes. At the same time, in February in the central part of the northwestern shelf, an absolute minimum of (Esp) is observed. This minimum is caused by the complete mixing and barotropization of the water column. The Esp maximum values are observed in the shelf in September – October. This is related to the intensification of the brackish water transport from the river mouths by mesoscale eddies. In the autumn period high values of Esp in the shelf and deep part of the basin are observed in the deeper layer, compare to summer months .Variability of the Esp vertical distribution coincides to the time variation of MLD. Variability of the submesoscale energy is of a pulsating character with the short-term intensifications and weakenings. Such variability is significantly related to the passing of the mesoscale fronts and the cross-shelf water transport caused by the eddies and upwellings, which lead to the increase of the baroclinic instability. Conclusions. Analysis of the seasonal and vertical variability of the submesoscale currents in the Black Sea deep and shelf zones evidences about the decisive role of the baroclinic instability triggered mainly by the heterogeneity of MLD on their dynamics.

scholarly journals Vertical Distribution of Phosphates in the Black Sea Based on the Expeditionary Data, 2016–2019

2021 ◽  
Vol 28 (5) ◽  
Author(s):  
S. I. Kondratev ◽  
D. S. Khoruzhii ◽  
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Keyword(s):  
Vertical Distribution ◽  
Black Sea ◽  
Organic Phosphorus ◽  
The Black Sea ◽  
Marine Hydrophysical Institute ◽  
Isopycnic Surface ◽  
Concentration Maximum ◽  
Suboxic Zone ◽  
Upper Mixed Layer ◽  
Upper Boundary

Purpose. The purpose of the study is to analyze the features of vertical distribution of phosphates and dissolved organic phosphorus (Porg) in the Black Sea at the present period. Methods and Results. The data obtained by the scientists of Marine Hydrophysical Institute in the Black Sea within the economic zone of Russia in 2016–2019 were used. At more than 200 deep-sea stations, a cassette of 12 bathometers (the Seabird-Electronics STD-instrument) was applied for taking hydrochemical samples at certain isopycnic surfaces, usually at σt = 16.30; 16.25; 16.20; 16.20; 16.15; 16.10; 16.05; 16.00; 15.95; 15.90; 15.80; 15.50, 14.0 kg/m3. At the coastal shallow-water stations, samples were taken at the 10 m intervals. Such a scheme permitted to carry out vertical sampling in the upper mixed layer and in the suboxic zone (including its upper boundary) with possible minimum of phosphates, to determine the depth of hydrogen sulfide formation and the location of the phosphates concentration maximum in the upper part of the anaerobic zone. Conclusions. From the surface to isopycn σt = 14.4 kg/m3, the content of phosphates and Porg does not exceed 0.1 µM; below this isopycnic surface, the phosphates concentration begins to increase, whereas of Porg remains at the same level. At all the profiles of the phosphates vertical distribution, the phosphates concentration minimum was recorded near the isopycnic surface σt = 15.8 kg/m3, and its maximum – near the isopycnic surface σt = 16.2 kg/m3. The minimum content of phosphates varied within 0–1.5 µM; in 2016–2017 the phosphates concentration maximum did not exceed 8 µM; in 2018, in many cases, it was higher than 12 µM, and once, near the Kerch Strait, it exceeded 17 µM. Increase in the magnitude of the maximum phosphates concentration (in the previous studies in 1988–2013, it did not exceed 8 µM) is assumed to be related to installation of the supports for constructing the Kerch Bridge.

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