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 37 (1) ◽  
Author(s):  
O. S. Puzina ◽  
A. A. Kubryakov ◽  
A. I. Mizyuk ◽  
◽  
◽  
...  
Keyword(s):  
Black Sea ◽  
Mixed Layer ◽  
Seasonal Variability ◽  
Baroclinic Instability ◽  
The Black Sea ◽  
Spectral Energy ◽  
Upper Mixed Layer ◽  
Mesoscale Currents ◽  
Vertical Variability

Purpose. The study is aimed at investigating seasonal variability and vertical distribution of the submesoscale 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 in the areas under investigation, seasonal variability of the sub-mesoscale currents energy is significantly different. At that, in both regions, seasonal variation of energy of the sub-mesoscale currents whose scale is less than 10 km (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 upper mixed layer during this period) in generation of sub-mesoscale processes in the Black Sea. At the same time, in February in the central part of the northwestern shelf, an absolute minimum of (Esp) is observed due to complete mixing and barotropization of the water column. The (Esp) maximum values are noted in September – October, that is related to intensification of the desalinated water cross-shelf transport from the river mouths being affected by the synoptic eddies. At the same time, in the autumn period in this region, the (Esp) high values are observed in the layer, the thickness of which is higher than that in summer (as well as in the central part of the sea). Dynamics of the (Esp) values distribution corresponds to the time variation of the upper mixed layer thickness. Variability of the sub-mesoscale currents energy is of a pulsating character with the short-term intensifications and weakenings. Such variability is significantly related to passing of the synoptic fronts and the cross-shelf water transport being influenced by the eddies and upwellings, which lead to baroclinic instability of waters. Conclusions. Seasonal and vertical variability of the spectral energy in the Black Sea deep and shelf zones testifies in favor of the decisive role of the water baroclinic instability arising due to heterogeneity of the upper mixed layer.

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 ◽  
◽  
◽  
...  
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.

Seasonal variations of the dinoflagellate algae Noctiluca scintillans abundance in the western Arabian Sea and the northern Black Sea

2021 ◽  
Author(s):  
Sergey Piontkovski ◽  
Khalid Al Hashmi ◽  
Yuliya Zagorodnaya ◽  
Irina Serikova ◽  
Vladislav Evstigneev ◽  
...  
Keyword(s):  
Black Sea ◽  
Mixed Layer ◽  
Algal Blooms ◽  
Arabian Sea ◽  
Temporal Dynamics ◽  
The Black Sea ◽  
Northeast Monsoon ◽  
Major Peak ◽  
Noctiluca Scintillans ◽  
Upper Mixed Layer

&lt;p&gt;Seasonal variability is a powerful component of the spatio-temporal dynamics of plankton communities, especially in the regions with oxygen-depleted waters. The Arabian Sea and the Black Sea are typical representatives of these regions. In both, the dinoflagellate Noctiluca scintillans (Macartney) Kofoid &amp; Swezy, 1921, is one of the abundant plankton species which forms algal blooms. Sampling on coastal stations in the upper mixed layer by the plankton nets with the 120-140 &amp;#181;m mesh size was carried out in 2004-2010. Monthly data were averaged over years. A comparison of seasonal patterns of Noctiluca abundance pointed to the persistence of a bimodal seasonal cycle in both regions. The major peak was observed during spring in the Black Sea and during the winter (Northeast) monsoon in the Arabian Sea. The timing of the second (minor) peak was different over regions as well. This peak was modulated by advection of seasonally fluctuating velocity of coastal currents which transport waters enriched by nutrients by coastal upwelling. The abundance of Noctiluca of the major peak (with the concentration around 1.5*10&lt;sup&gt;6&lt;/sup&gt; cells m&lt;sup&gt;-3&lt;/sup&gt;) was from one to two orders as much high in the western Arabian Sea compared to the northern Black Sea. The remotely sensed chlorophyll-a concentration during the time of the major seasonal peak exhibited a fivefold difference over these regions. In terms of nutrient&lt;sub&gt;&lt;/sub&gt;concentration in the upper mixed layer (in particular, nitrates and silicates), a difference of about one order of magnitude was observed.&lt;/p&gt;

scholarly journals Interannual Variability of the Wind-Wave Regime Parameters in the Black Sea

2020 ◽  
Vol 27 (5) ◽  
Author(s):  
P. N. Lishaev ◽  
V. V. Knysh ◽  
G. K. Korotaev ◽  
◽  
◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Black Sea ◽  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Sea Surface ◽  
Temperature Fields ◽  
The Black Sea ◽  
Layer Depth ◽  
Upper Mixed Layer

Purpose. The investigation is aimed at increasing accuracy of the temperature field reconstruction in the Black Sea upper layer. For this purpose, satellite observations of the sea surface temperature and the three-dimensional fields of temperature (in the 50–500 m layer) and salinity (in the 2.5–500 m layer) pseudo-measurements, previously calculated by the altimetry and the Argo floats data, were jointly assimilated in the Marine Hydrophysical Institute model. Methods and Results. Assimilation of the sea surface temperature satellite observations is the most effective instrument in case the discrepancies between the sea surface and the model temperatures are extrapolated over the upper mixed layer depth up to its lower boundary. Having been analyzed, the temperature profiles resulted from the forecast calculation for 2012 and from the Argo float measurements made it possible to obtain a simple criterion (bound to the model grid) for determining the upper mixed layer depth, namely the horizon on which the temperature gradient was less or equal to ≤ 0.017 °C/m. Within the upper mixed layer depth, the nudging procedure of satellite temperature measurements with the selected relaxation factor and the measurement errors taken into account was used in the heat transfer equation. The temperature and salinity pseudo-measurements were assimilated in the model by the previously proposed adaptive statistics method. To test the results of the sea surface temperature assimilation, the Black Sea hydrophysical fields were reanalyzed for 2012. The winter-spring period (January – April, December) is characterized by the high upper mixed layer depths, well reproducible by the Pacanowski – Philander parameterization, and also by the low values (as compared to the measured ones) of the basin-averaged monthly mean square deviations of the simulated temperature fields. The increased mean square deviations in July – September are explained by absence of the upper mixed layer in the temperature profiles measured by the Argo floats that is not reproduced by the Pacanowski – Philander parameterization. Conclusions. The algorithm for assimilating the sea surface temperature together with the profiles of the temperature and salinity pseudo-measurements reconstructed from the altimetry data was realized. Application of the upper mixed layer depths estimated by the temperature vertical profiles made it possible to correct effectively the model temperature by the satellite-derived sea surface temperature, especially for a winter-spring period. It permitted to reconstruct the temperature fields in the sea upper layer for 2012 with acceptable accuracy.

scholarly journals Light Absorption by Phytoplankton in the Upper Mixed Layer of the Black Sea: Seasonality and Parametrization

2017 ◽  
Vol 4 ◽  
Author(s):  
Tanya Churilova ◽  
Vyacheslav Suslin ◽  
Olga Krivenko ◽  
Tatiana Efimova ◽  
Nataliia Moiseeva ◽  
...  
Keyword(s):  
Black Sea ◽  
Mixed Layer ◽  
Light Absorption ◽  
The Black Sea ◽  
Upper Mixed Layer

scholarly journals Reconstructing the Black Sea Hydrophysical Fields Including Assimilation of the Sea Surface Temperature, and the Temperature and Salinity Pseudo-Measurements in the Model

2020 ◽  
Vol 36 (5) ◽  
Author(s):  
P. N. Lishaev ◽  
V. V. Knysh ◽  
G. K. Korotaev ◽  
◽  
◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Black Sea ◽  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Sea Surface ◽  
Temperature Fields ◽  
The Black Sea ◽  
Layer Depth ◽  
Upper Mixed Layer

Purpose. The investigation is aimed at increasing accuracy of the temperature field reconstruction in the Black Sea upper layer. For this purpose, satellite observations of the sea surface temperature and the three-dimensional fields of temperature (in the 50–500 m layer) and salinity (in the 2.5–500 m layer) pseudo-measurements, previously calculated by the altimetry and the Argo floats data, were jointly assimilated in the Marine Hydrophysical Institute model. Methods and Results. Assimilation of the sea surface temperature satellite observations is the most effective instrument in case the discrepancies between the sea surface and the model temperatures are extrapolated over the upper mixed layer depth up to its lower boundary. Having been analyzed, the temperature profiles resulted from the forecast calculation for 2012 and from the Argo float measurements made it possible to obtain a simple criterion (bound to the model grid) for determining the upper mixed layer depth, namely the horizon on which the temperature gradient was less or equal to 0.017°C/m. Within the upper mixed layer depth, the nudging procedure of satellite temperature measurements with the selected relaxation factor and the measurement errors taken into account was used in the heat transfer equation. The temperature and salinity pseudo-measurements were assimilated in the model by the previously proposed adaptive statistics method. To test the results of the sea surface temperature assimilation, the Black Sea hydrophysical fields were reanalyzed for 2012. The winterspring period (January – April, December) is characterized by the high upper mixed layer depths, well reproducible by the Pacanowsci – Philander parameterization, and also by the low values (as compared to the measured ones) of the basin-averaged monthly mean square deviations of the simulated temperature fields. The increased mean square deviations in July – September are explained by absence of the upper mixed layer in the temperature profiles measured by the Argo floats that is not reproduced by the Pacanowsci – Philander parameterization. Conclusions. The algorithm for assimilating the sea surface temperature together with the profiles of the temperature and salinity pseudo-measurements reconstructed from the altimetry data was realized. Application of the upper mixed layer depths estimated by the temperature vertical profiles made it possible to correct effectively the model temperature by the satellite-derived sea surface temperature, especially for a winter-spring period. It permitted to reconstruct the temperature fields in the sea upper layer for 2012 with acceptable accuracy.

scholarly journals Feature of formation of the Black Sea surface layer temperature during air cold intrusions

2019 ◽  
Vol 487 (4) ◽  
pp. 443-447
Author(s):  
A. A. Sizov ◽  
T. M. Bayankina
Keyword(s):  
Surface Layer ◽  
Black Sea ◽  
Mixed Layer ◽  
Sea Surface ◽  
The Black Sea ◽  
Intermediate Water ◽  
Seasonal Thermocline ◽  
Upper Mixed Layer ◽  
Surface Layer Temperature

Application of the results of the drifter observations performed in the western Black Sea permitted to show that during air cold intrusions (CI) in winter accompanied by the wind (10 m/c and more), the upper mixed layer (UML) was cooled by 0,1-0,2 °C in course of a day. At that the seasonal thermocline (ST) and the cold intermediate water (CIW) sink deeper; after CI is over these layers rise to the depths smaller than their previous ones. It results in decrease of temperature in UML and its increase, as compared to the period preceding CI, in the layer below ST. The process of the sea upper layer mixing is explained by the fact that anti-cyclonic mesoscale vortices are involved in it.

Role of suspended matter in controlling beryllium-7 (7Be) in the Black Sea surface layer

2021 ◽  
pp. 103513
Author(s):  
Dmitrii A. Kremenchutskii ◽  
Gennady F. Batrakov ◽  
Illarion I. Dovhyi ◽  
Yury A. Sapozhnikov
Keyword(s):  
Surface Layer ◽  
Black Sea ◽  
Suspended Matter ◽  
Sea Surface ◽  
The Black Sea

Georgian Historians and the Ideological Confrontation Between East and West

2021 ◽  
Vol 30 (1) ◽  
pp. 153-164
Author(s):  
George Gotsiridze
Keyword(s):  
Soviet Union ◽  
Cultural Values ◽  
Black Sea ◽  
The Black Sea ◽  
Black Sea Region ◽  
The Soviet Union ◽  
Long Time ◽  
Science And Culture ◽  
East And West

The work, on the one hand, highlights the mission of Europe, as an importer of knowledge, which has for centuries been the center of gravity for the whole world, and, on the other hand, the role of the Black Sea Region, as an important part of the Great Silk Road, which had also for a long time been promoting the process of rap-prochement and exchange of cultural values between East and West peoples, until it became the ‘inner lake’ of the Ottoman Empire, and today it reverts the function of rapproching and connecting civilizations. The article shows the importance of the Black Sea countries in maintaining overall European stability and in this context the role of historical science. On the backdrop of the ideological confrontation between Georgian historians being inside and outside the Iron Curtain, which began with the foundation of the Soviet Union, the research sheds light on the merit of the Georgian scholars-in-exile for both popularization of the Georgian culture and science in Eu-rope and for importing advanced (European) scientific knowledge to Georgia. Ex-change of knowledge in science and culture between the Black Sea region and Europe will enrich and complete each other through impact and each of them will have unique, inimitative features.

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