Pub Date : 2019-12-01DOI: 10.22449/0233-7584-2019-6-621-632
S. Kochergin, V. Fomin
Purpose. The aim of the paper is to construct and to validate the variational procedure for determining the pollutant concentration and the water flow out velocity at the underwater source exit, as well as to analyze the algorithm sensitivity to the level of random noise in the measurement data. Methods and Results. The flow field was calculated using the three-dimensional baroclinic σ-coordinate model of water circulation. Realization of the pollution transfer model included application of the TVD-type monotone schemes. The temperature and salinity initial profiles were preset based on the results of probing in the area of the underwater release, and the characteristic velocity of the back-ground currents was defined using the data of the ADCP-measurements. The input parameters of the problem were identified by means of the iterative procedure for minimizing the quadratic functional. The numerical experiments on identifying parameters of the underwater pollution source showed that if noise was left out of account, the original parameters were reconstructed with a relative error < 1%. It is shown that the identification problem becomes of better conditionality in case the data from more informative points of the measurement scheme are assimilated. Conclusions. Based on the analysis of the numerical experiments, the linearization algorithm is shown to be able to identify the parameters of the underwater source. The proposed algorithms can be used to solve a wide class of environmental problems, as well as to interpret and to plan the field experiments aimed at studying the wastewater distribution in the coastal waters.
{"title":"Variational Identification of Input Parameters in the Model of Distribution of the Pollutants from the Underwater Source","authors":"S. Kochergin, V. Fomin","doi":"10.22449/0233-7584-2019-6-621-632","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-6-621-632","url":null,"abstract":"Purpose. The aim of the paper is to construct and to validate the variational procedure for determining the pollutant concentration and the water flow out velocity at the underwater source exit, as well as to analyze the algorithm sensitivity to the level of random noise in the measurement data. Methods and Results. The flow field was calculated using the three-dimensional baroclinic σ-coordinate model of water circulation. Realization of the pollution transfer model included application of the TVD-type monotone schemes. The temperature and salinity initial profiles were preset based on the results of probing in the area of the underwater release, and the characteristic velocity of the back-ground currents was defined using the data of the ADCP-measurements. The input parameters of the problem were identified by means of the iterative procedure for minimizing the quadratic functional. The numerical experiments on identifying parameters of the underwater pollution source showed that if noise was left out of account, the original parameters were reconstructed with a relative error < 1%. It is shown that the identification problem becomes of better conditionality in case the data from more informative points of the measurement scheme are assimilated. Conclusions. Based on the analysis of the numerical experiments, the linearization algorithm is shown to be able to identify the parameters of the underwater source. The proposed algorithms can be used to solve a wide class of environmental problems, as well as to interpret and to plan the field experiments aimed at studying the wastewater distribution in the coastal waters.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46066445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.22449/0233-7584-2019-6-585-599
V. Agoshkov, V. Shutyaev, E. Parmuzin, N. Zakharova, T. Sheloput, N. Lezina
Purpose. In order to simulate the sea hydrothermodynamics, the problem of variational assimilation of the sea surface temperature data is solved. The data assimilation permits to adjust the numerical model calculations to the measurement data obtained in the environment under study. Methods and Results. The mathematical model of hydrothermodynamics of the Black and Azov seas, developed at the Institute of Numerical Mathematics of RAS and written in the sigma coordinate system, is considered. The distinctive feature of the model consists in applying the splitting method to physical processes and spatial coordinates that can significantly simplify the variational data assimilation algorithm. The problem of variational assimilation of the sea surface temperature data is formulated. A cost functional has been introduced; it includes the control function – heat flux at the sea upper boundary and satellite observations of the sea surface temperature. The necessary condition for the functional minimum is reformulated through the optimality system including the direct and adjoint problems, and the control condition. Using the variational assimilation of the satellite-derived observations, the algorithm for solving the stated problem was developed. It takes into account the observational errors’ covariance matrix calculated based on the statistical characteristics of the sea surface temperature observational data. The algorithm implies a sequential solution of the optimality system in the iterative process with the specially selected iterative parameter. The results of numerical solution of this problem are represented by the example of the Black and Azov seas. Conslusion. The results of numerical modeling with the observational data assimilation and without it are compared; efficiency of the observational data assimilation procedures is shown. Influence of the sea surface temperature assimilation upon the other system parameters is investigated. It is shown that when assimilating the sea surface temperature, only temperature in the upper layers is affected, whereas, provided that the depth is sufficient, the profile in the lower layers remains practically unchanged. The impact on the other system parameters is either minimal or not manifested at all.
{"title":"Variational Data Assimilation in the Mathematical Model of the Black Sea Dynamics","authors":"V. Agoshkov, V. Shutyaev, E. Parmuzin, N. Zakharova, T. Sheloput, N. Lezina","doi":"10.22449/0233-7584-2019-6-585-599","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-6-585-599","url":null,"abstract":"Purpose. In order to simulate the sea hydrothermodynamics, the problem of variational assimilation of the sea surface temperature data is solved. The data assimilation permits to adjust the numerical model calculations to the measurement data obtained in the environment under study. Methods and Results. The mathematical model of hydrothermodynamics of the Black and Azov seas, developed at the Institute of Numerical Mathematics of RAS and written in the sigma coordinate system, is considered. The distinctive feature of the model consists in applying the splitting method to physical processes and spatial coordinates that can significantly simplify the variational data assimilation algorithm. The problem of variational assimilation of the sea surface temperature data is formulated. A cost functional has been introduced; it includes the control function – heat flux at the sea upper boundary and satellite observations of the sea surface temperature. The necessary condition for the functional minimum is reformulated through the optimality system including the direct and adjoint problems, and the control condition. Using the variational assimilation of the satellite-derived observations, the algorithm for solving the stated problem was developed. It takes into account the observational errors’ covariance matrix calculated based on the statistical characteristics of the sea surface temperature observational data. The algorithm implies a sequential solution of the optimality system in the iterative process with the specially selected iterative parameter. The results of numerical solution of this problem are represented by the example of the Black and Azov seas. Conslusion. The results of numerical modeling with the observational data assimilation and without it are compared; efficiency of the observational data assimilation procedures is shown. Influence of the sea surface temperature assimilation upon the other system parameters is investigated. It is shown that when assimilating the sea surface temperature, only temperature in the upper layers is affected, whereas, provided that the depth is sufficient, the profile in the lower layers remains practically unchanged. The impact on the other system parameters is either minimal or not manifested at all.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42974216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.22449/1573-160x-2019-5-374-386
Yu. V. Manilyuk, D. Lazorenko, V. Fomin
{"title":"Resonance Oscillations in the System of Adjacent Bays","authors":"Yu. V. Manilyuk, D. Lazorenko, V. Fomin","doi":"10.22449/1573-160x-2019-5-374-386","DOIUrl":"https://doi.org/10.22449/1573-160x-2019-5-374-386","url":null,"abstract":"","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46176485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.22449/1573-160x-2019-5-387-396
A. Bukatov, E. A. Pavlenko, N. M. Solovei
{"title":"Accuracy Estimation of the Black Sea Circulation Modeling Results Obtained at Different Bottom Topography","authors":"A. Bukatov, E. A. Pavlenko, N. M. Solovei","doi":"10.22449/1573-160x-2019-5-387-396","DOIUrl":"https://doi.org/10.22449/1573-160x-2019-5-387-396","url":null,"abstract":"","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41945430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.22449/1573-160x-2019-4-341-349
A. S. Kuznetsov, Yu.I. Shapovalov, R. O. Shapovalov
{"title":"Results of Monitoring the Surface Fields Dynamics in the Black Sea Waters Using a Ferry Box System","authors":"A. S. Kuznetsov, Yu.I. Shapovalov, R. O. Shapovalov","doi":"10.22449/1573-160x-2019-4-341-349","DOIUrl":"https://doi.org/10.22449/1573-160x-2019-4-341-349","url":null,"abstract":"","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41758603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-09DOI: 10.22449/0233-7584-2019-4-355-366
Алексей Львович Чикин, А. В. Клещенков, Любовь Григорьевна Чикина
Представлена математическая модель, объединяющая в себе две модели: модель гидродинамики Азовского моря и модель движения воды в основных рукавах дельты Дона. Предложенный подход позволяет по рассчитанным значениям уровня воды в принимающем водоеме определять гидродинамические характеристики руслового потока в основных рукавах дельты Дона в зависимости от ветровой ситуации в Азовском море и Таганрогском заливе. Это особо ценно для бесшовного анализа общей гидродинамики в устьевой области Дона, что может оказаться полезным в будущем для оценки транспорта общей взвеси, микропластика, интрузий соленых вод и исследования иных типов загрязнения. Сравнение наблюдавшихся и расчетных значений уровня воды в исследованной области демонстрирует удовлетворительное качество получаемых результатов, что говорит о достаточной адекватности представленной модели, однако расчетные значения в основном несколько завышены по сравнению с зарегистрированными данными. Возможна дополнительная корректировка расчетных значений с помощью поправочных коэффициентов. Предлагаемая методика может применяться и для других водоемов при совместном расчете течений в устьевых руслах и ветровых течений в принимающем водоеме.
{"title":"ЧИСЛЕННОЕ ИССЛЕДОВАНИЕ ВЛИЯНИЯ ВЕТРОВОЙ СИТУАЦИИ В ТАГАНРОГСКОМ ЗАЛИВЕ НА УРОВЕНЬ ВОДЫ В ДЕЛЬТЕ ДОНА, \"Наука юга России\"","authors":"Алексей Львович Чикин, А. В. Клещенков, Любовь Григорьевна Чикина","doi":"10.22449/0233-7584-2019-4-355-366","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-4-355-366","url":null,"abstract":"Представлена математическая модель, объединяющая в себе две модели: модель гидродинамики Азовского моря и модель движения воды в основных рукавах дельты Дона. Предложенный подход позволяет по рассчитанным значениям уровня воды в принимающем водоеме определять гидродинамические характеристики руслового потока в основных рукавах дельты Дона в зависимости от ветровой ситуации в Азовском море и Таганрогском заливе. Это особо ценно для бесшовного анализа общей гидродинамики в устьевой области Дона, что может оказаться полезным в будущем для оценки транспорта общей взвеси, микропластика, интрузий соленых вод и исследования иных типов загрязнения. Сравнение наблюдавшихся и расчетных значений уровня воды в исследованной области демонстрирует удовлетворительное качество получаемых результатов, что говорит о достаточной адекватности представленной модели, однако расчетные значения в основном несколько завышены по сравнению с зарегистрированными данными. Возможна дополнительная корректировка расчетных значений с помощью поправочных коэффициентов. Предлагаемая методика может применяться и для других водоемов при совместном расчете течений в устьевых руслах и ветровых течений в принимающем водоеме.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68625083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-01DOI: 10.22449/0233-7584-2019-4-341-354
O. Dymova, N. Miklashevskaya
Purpose. Accuracy of the reconstructed hydrophysical fields calculated using different data on bottom topography is estimated in order to determine the depth array corresponding to the modern tasks of the Black Sea circulation modeling with high spatial resolution. Methods and Results. Two numerical experiments on modeling the circulation were carried out based on the Marine Hydrophysical Institute, Russian Academy of Sciences (MHI RAS) ocean model. Horizontal resolution was 1.6 km, 27 irregular z -horizons were preset vertically and the SKIRON/Eta data (2011) were used as the atmospheric forcing for both cases. Difference between the experiments consisted in application of different bathymetry. In the first experiment, the bottom topography was preset in accordance with the Black Sea depths from the MHI Ocean Data Bank with the 5-minute resolution; in the second one – based on the European Marine Observation and Data Network (EMODnet) depth array with the 1/8ꞌ resolution. The calculated hydrophysical fields were compared with the temperature and salinity measurements, and satellite images of the sea surface temperature. The analysis showed that application of the depths data of higher resolution permitted to improve accuracy of thermohydrodynamic characteristics of the Black Sea circulation in the 30–300 m layer. The integral values of the eddy kinetic energy and the mean current kinetic energy for two experiments were also considered for both of the experiments. The results of the comparative analysis demonstrate the fact that, at the bottom topography with higher resolution taken into account, in the simulated system the mechanisms of energy redistribution between currents and eddies changed during intensive storm impacts. Conclusions. The results of the present research permit to conclude that in the experiment with a smoother bottom relief, increase of kinetic energy both of the eddies and currents was due to barotropic instability. In case of more complex bathymetry, the eddy kinetic energy increased mainly owing to the processes associated with baroclinic instability. eddy, kinetic energy. Acknowledgements: t he authors are grateful to the reviewers for their helpful comments. Experi ment 1 and comparative analyses were performed in the framework of the state task № 0827-2019-0003 “Fundamental study of oceanological processes conditioning state and evolution of marine environment under effect of anthropogenic factors based on observational and modeling methods”. The EMODnet data adaptation for the MHI-model and experiment 2 were carried out under support of the Russian Foundation for Basic Research (project No. 18-05-00353 A).
{"title":"Accuracy Estimation of the Black Sea Circulation Modeling Results Obtained at Different Bottom Topography","authors":"O. Dymova, N. Miklashevskaya","doi":"10.22449/0233-7584-2019-4-341-354","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-4-341-354","url":null,"abstract":"Purpose. Accuracy of the reconstructed hydrophysical fields calculated using different data on bottom topography is estimated in order to determine the depth array corresponding to the modern tasks of the Black Sea circulation modeling with high spatial resolution. Methods and Results. Two numerical experiments on modeling the circulation were carried out based on the Marine Hydrophysical Institute, Russian Academy of Sciences (MHI RAS) ocean model. Horizontal resolution was 1.6 km, 27 irregular z -horizons were preset vertically and the SKIRON/Eta data (2011) were used as the atmospheric forcing for both cases. Difference between the experiments consisted in application of different bathymetry. In the first experiment, the bottom topography was preset in accordance with the Black Sea depths from the MHI Ocean Data Bank with the 5-minute resolution; in the second one – based on the European Marine Observation and Data Network (EMODnet) depth array with the 1/8ꞌ resolution. The calculated hydrophysical fields were compared with the temperature and salinity measurements, and satellite images of the sea surface temperature. The analysis showed that application of the depths data of higher resolution permitted to improve accuracy of thermohydrodynamic characteristics of the Black Sea circulation in the 30–300 m layer. The integral values of the eddy kinetic energy and the mean current kinetic energy for two experiments were also considered for both of the experiments. The results of the comparative analysis demonstrate the fact that, at the bottom topography with higher resolution taken into account, in the simulated system the mechanisms of energy redistribution between currents and eddies changed during intensive storm impacts. Conclusions. The results of the present research permit to conclude that in the experiment with a smoother bottom relief, increase of kinetic energy both of the eddies and currents was due to barotropic instability. In case of more complex bathymetry, the eddy kinetic energy increased mainly owing to the processes associated with baroclinic instability. eddy, kinetic energy. Acknowledgements: t he authors are grateful to the reviewers for their helpful comments. Experi ment 1 and comparative analyses were performed in the framework of the state task № 0827-2019-0003 “Fundamental study of oceanological processes conditioning state and evolution of marine environment under effect of anthropogenic factors based on observational and modeling methods”. The EMODnet data adaptation for the MHI-model and experiment 2 were carried out under support of the Russian Foundation for Basic Research (project No. 18-05-00353 A).","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47303367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-01DOI: 10.22449/0233-7584-2019-4-322-340
V. Ivanov, T. Shul’ga, A. Bagaev, A. Medvedeva, T. Plastun, L. Verzhevskaia, I. A. Svishcheva
Purpose . The purpose consists in a combined analysis of satellite observations of surface manifestations of internal waves near the Crimean coast and the results of numerical simulation of influence of seasonal thermohaline conditions and the relief on their structure, dynamics and intensification. Methods and Results. Based on the analysis of remote sensing data using high-resolution sensors of the Landsat -8 and Sentinel -2 satellites and the theoretical estimates, the main spatial and temporal characteristics of the internal waves on the Black Sea shelf near the Heracles Peninsula were determined. According to the temperature and salinity data obtained from the satellite measurements and the research vessels measurements in 1951–2008 from the Oceanographic Data Bank of Marine Hydrophysical Institute, the structure of density stratification was investigated, and buoyancy frequency profiles in the shelf and slope area from Yevpatoria to Yalta were obtained. Vertical velocity profiles of internal waves of the first three modes on the shelf were constructed. It was revealed that phase velocity of the internal waves of the first mode in the deep-sea part varied within the range of 2.6–5 m/s, the waves of the second mode – within 1.1–2.3 m/s, and the waves of the third mode – within 0.7–1.4 m/s. The average length of the waves detected from the satellite data was 0.4 km; the longest waves, about 1.1 km, were observed most often between Yevpatoria and Sevastopol, propagating predominantly to the northeast. Within the same train, wave dispersion occurred resulting in the wavelength diminution to 0.1–0.3 km. Conclusions. The stated assumption on the cause of generation of intense internal waves conditioned by the interaction of the Rim Current jet with the shelf edge was confirmed by the results of numerical calculations. Spatial and temporal characteristics of the internal waves, the integrated data of remote sensing and the modeling results make it possible to estimate vertical exchange at the shelf and to determine the depth of the maximum Brunt–Väisälä frequency.
{"title":"Internal Waves on the Black Sea Shelf near the Heracles Peninsula: Modeling and Observation","authors":"V. Ivanov, T. Shul’ga, A. Bagaev, A. Medvedeva, T. Plastun, L. Verzhevskaia, I. A. Svishcheva","doi":"10.22449/0233-7584-2019-4-322-340","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-4-322-340","url":null,"abstract":"Purpose . The purpose consists in a combined analysis of satellite observations of surface manifestations of internal waves near the Crimean coast and the results of numerical simulation of influence of seasonal thermohaline conditions and the relief on their structure, dynamics and intensification. Methods and Results. Based on the analysis of remote sensing data using high-resolution sensors of the Landsat -8 and Sentinel -2 satellites and the theoretical estimates, the main spatial and temporal characteristics of the internal waves on the Black Sea shelf near the Heracles Peninsula were determined. According to the temperature and salinity data obtained from the satellite measurements and the research vessels measurements in 1951–2008 from the Oceanographic Data Bank of Marine Hydrophysical Institute, the structure of density stratification was investigated, and buoyancy frequency profiles in the shelf and slope area from Yevpatoria to Yalta were obtained. Vertical velocity profiles of internal waves of the first three modes on the shelf were constructed. It was revealed that phase velocity of the internal waves of the first mode in the deep-sea part varied within the range of 2.6–5 m/s, the waves of the second mode – within 1.1–2.3 m/s, and the waves of the third mode – within 0.7–1.4 m/s. The average length of the waves detected from the satellite data was 0.4 km; the longest waves, about 1.1 km, were observed most often between Yevpatoria and Sevastopol, propagating predominantly to the northeast. Within the same train, wave dispersion occurred resulting in the wavelength diminution to 0.1–0.3 km. Conclusions. The stated assumption on the cause of generation of intense internal waves conditioned by the interaction of the Rim Current jet with the shelf edge was confirmed by the results of numerical calculations. Spatial and temporal characteristics of the internal waves, the integrated data of remote sensing and the modeling results make it possible to estimate vertical exchange at the shelf and to determine the depth of the maximum Brunt–Väisälä frequency.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46953612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-01DOI: 10.22449/0233-7584-2019-4-307-321
S. Demyshev, S. V. Dovgaya, M. Shokurov
Purpose. The main objectives of the study consisted in analyzing the Marmara Sea energy and in identifying the basic reasons for formation of its circulation features in 2008. Methods and Results. The numerical experiment on modeling the Marmara Sea circulation and evaluating its energy characteristics on the example of 2008 was carried out based on the eddyresolving nonlinear hydrodynamic model of Marine Hydrophysical Institute, RAS. The horizontal resolution of the model was 1.22 × 0.83 km, 18 horizons were used over vertical and the time step was 0.5 min. Temperature, salinity and water discharge through the Bosporus and the Dardanelles were preset according to the available measurement data. The applied fields of atmospheric forcing were obtained from the calculation by the regional atmospheric model MM5. The volume-integrated and year-averaged contributions of the terms in the equations of the kinetic and potential energy budgets were analyzed. The basic factors of change in the Marmara Sea kinetic energy consisted in the buoyancy force action, wind, and vertical and horizontal mixing. Having been analyzed, the volume-average summands in the equation of rate of the kinetic energy change have shown that the wind-induced energy influx was compensated mainly by vertical friction, and the buoyancy force action – by horizontal friction. On the average, in course of a year the potential energy changed mainly due to its horizontal transport conditioned by the effect of the currents located in front of the straits, vertical diffusion and the buoyancy force impact. The results of analysis of the energy transitions permitted to reveal that in the upper sea layer, the mesoscale vortices were formed directly under the wind influence and as a result of the currents’ baroclinic instability. Generation of the submesoscale vortices in the coastal regions was affected predominantly by the processes of baroclinic instability. In the region near the Bosporus, increase of the horizontal gradients in the density field and, consequently, intensification of dynamic processes are the results of inflow of the Black Sea waters with lower density. Conclusions. Study of the energy characteristics of the Marmara Sea water circulation permitted to conclude that baroclinic instability and wind are two of the basic sources of eddy formation in this basin.
{"title":"Energy Characteristics of the Marmara Sea Water Circulation in 2008","authors":"S. Demyshev, S. V. Dovgaya, M. Shokurov","doi":"10.22449/0233-7584-2019-4-307-321","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-4-307-321","url":null,"abstract":"Purpose. The main objectives of the study consisted in analyzing the Marmara Sea energy and in identifying the basic reasons for formation of its circulation features in 2008. Methods and Results. The numerical experiment on modeling the Marmara Sea circulation and evaluating its energy characteristics on the example of 2008 was carried out based on the eddyresolving nonlinear hydrodynamic model of Marine Hydrophysical Institute, RAS. The horizontal resolution of the model was 1.22 × 0.83 km, 18 horizons were used over vertical and the time step was 0.5 min. Temperature, salinity and water discharge through the Bosporus and the Dardanelles were preset according to the available measurement data. The applied fields of atmospheric forcing were obtained from the calculation by the regional atmospheric model MM5. The volume-integrated and year-averaged contributions of the terms in the equations of the kinetic and potential energy budgets were analyzed. The basic factors of change in the Marmara Sea kinetic energy consisted in the buoyancy force action, wind, and vertical and horizontal mixing. Having been analyzed, the volume-average summands in the equation of rate of the kinetic energy change have shown that the wind-induced energy influx was compensated mainly by vertical friction, and the buoyancy force action – by horizontal friction. On the average, in course of a year the potential energy changed mainly due to its horizontal transport conditioned by the effect of the currents located in front of the straits, vertical diffusion and the buoyancy force impact. The results of analysis of the energy transitions permitted to reveal that in the upper sea layer, the mesoscale vortices were formed directly under the wind influence and as a result of the currents’ baroclinic instability. Generation of the submesoscale vortices in the coastal regions was affected predominantly by the processes of baroclinic instability. In the region near the Bosporus, increase of the horizontal gradients in the density field and, consequently, intensification of dynamic processes are the results of inflow of the Black Sea waters with lower density. Conclusions. Study of the energy characteristics of the Marmara Sea water circulation permitted to conclude that baroclinic instability and wind are two of the basic sources of eddy formation in this basin.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68625055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-01DOI: 10.22449/0233-7584-2019-4-367-383
S. Kondratev
Purpose. The paper is aimed at studying the present state of water ecology of the Black Sea northwestern shelf (NWS). Since the early 60-ies of the last century, ecology in this region deteriorated seriously due to intensive anthropogenic load that resulted in eutrophication of waters and regular fish mortality in the warm period of a year. Methods and Results. In 1997-2013 Marine Hydrophysical Institute realized 7 hydrological and hydrochemical expeditions near the Danube mouth. The dissolved oxygen and nutrients (nitrate, nitrite, phosphate and silicic acid) contents were analyzed in the water samples collected at the bottom (0.5-1 m above the bottom) and surface (0-1 m) horizons. Conclusions. Revealed are three hydrological-hydrochemical situations typical of the region: distribution of the transformed Danube flow far to the east, pressing of the Danube flow to the west coast of the Black Sea and alongshore upwelling. Silica and nitrate are rapidly and almost completely extracted from the seawater (the latter one – even in early winter) during photosynthesis in the surface waters on the NWS. The processes of particulate organic matter mineralization in the bottom waters of the NWS are assumed to be an additional source of silicic acid and nitrates. As for silicic acid, the process takes place during a warm season, and for nitrates – even in early winter. The alongshore upwelling in summer can lead to oxygen deficiency in the coastal waters and that, in its turn, can result in fish mortality on the shelf. The waters of the northwestern shelf open part which, in autumn 2010, pressed the Danube transformed freshwater flow to the Black Sea west coast, contained very small concentrations of biogenic elements (low content of silicic acid should be particularly noted). The study confirms the fact that the hazardous process of change in the phytoplankton species composition still continues, thus, altering the whole food chain in the Black Sea.
{"title":"Three Typical Hydrological-Hydrochemical Situations Near the Danube River Mouth Based on the Marine Hydrophysical Institute Research Expeditions in 1997-2013","authors":"S. Kondratev","doi":"10.22449/0233-7584-2019-4-367-383","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-4-367-383","url":null,"abstract":"Purpose. The paper is aimed at studying the present state of water ecology of the Black Sea northwestern shelf (NWS). Since the early 60-ies of the last century, ecology in this region deteriorated seriously due to intensive anthropogenic load that resulted in eutrophication of waters and regular fish mortality in the warm period of a year. Methods and Results. In 1997-2013 Marine Hydrophysical Institute realized 7 hydrological and hydrochemical expeditions near the Danube mouth. The dissolved oxygen and nutrients (nitrate, nitrite, phosphate and silicic acid) contents were analyzed in the water samples collected at the bottom (0.5-1 m above the bottom) and surface (0-1 m) horizons. Conclusions. Revealed are three hydrological-hydrochemical situations typical of the region: distribution of the transformed Danube flow far to the east, pressing of the Danube flow to the west coast of the Black Sea and alongshore upwelling. Silica and nitrate are rapidly and almost completely extracted from the seawater (the latter one – even in early winter) during photosynthesis in the surface waters on the NWS. The processes of particulate organic matter mineralization in the bottom waters of the NWS are assumed to be an additional source of silicic acid and nitrates. As for silicic acid, the process takes place during a warm season, and for nitrates – even in early winter. The alongshore upwelling in summer can lead to oxygen deficiency in the coastal waters and that, in its turn, can result in fish mortality on the shelf. The waters of the northwestern shelf open part which, in autumn 2010, pressed the Danube transformed freshwater flow to the Black Sea west coast, contained very small concentrations of biogenic elements (low content of silicic acid should be particularly noted). The study confirms the fact that the hazardous process of change in the phytoplankton species composition still continues, thus, altering the whole food chain in the Black Sea.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44481982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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