Pub Date : 2020-02-01DOI: 10.22449/0233-7584-2020-1-53-65
V. Mankovsky, E. Mankovskaya
Purpose. The aim of the paper is to study spatial variability of the Mediterranean Sea water optical features as well as to supply the database with additional information on the water optical characteristics required for constructing the regional hydrooptical models. Methods and Results. The data on optical characteristics of the southern Mediterranean Sea waters resulted from the passing measurements in the 2 cruise of R/V Gorizont in May, 1998 are used in the study. In the water samples from the sea surface layers, the spectral coefficients of beam attenuation and light scattering phase function were measured. Spatial variability of the seawater hydrooptical characteristics from the Strait of Gibraltar to the Dardanelles is considered and analyzed. The equation for the relationship between the asymmetry coefficient of the scattering phase function and the scattering coefficient in the Mediterranean Sea waters is obtained. Conclusions. The data characterizing spatial variability of the southern Mediterranean Sea water optical features in spring are obtained. The coefficients of beam attenuation and scattering in the surface waters decrease gradually from the western Mediterranean Sea to its eastern part. In the Aegean Sea near the Dardanelles, the Marmara Sea waters differing by their high coefficients of beam attenuation and scattering were observed. As for the basic parameters, the scattering phase functions in the Mediterranean Sea waters are similar to those in the Atlantic tropical waters. In the Mediterranean Sea waters as well as in the other water basins, the relationship between the asymmetry coefficient of the light scattering phase function and the scattering coefficient is observed; it is manifested in increase of the phase function asymmetry coefficient with the scattering coefficient.
{"title":"Spatial Variability of Water Optical Characteristics in the Southern Mediterranean Sea in Spring (May, 1998)","authors":"V. Mankovsky, E. Mankovskaya","doi":"10.22449/0233-7584-2020-1-53-65","DOIUrl":"https://doi.org/10.22449/0233-7584-2020-1-53-65","url":null,"abstract":"Purpose. The aim of the paper is to study spatial variability of the Mediterranean Sea water optical features as well as to supply the database with additional information on the water optical characteristics required for constructing the regional hydrooptical models. Methods and Results. The data on optical characteristics of the southern Mediterranean Sea waters resulted from the passing measurements in the 2 cruise of R/V Gorizont in May, 1998 are used in the study. In the water samples from the sea surface layers, the spectral coefficients of beam attenuation and light scattering phase function were measured. Spatial variability of the seawater hydrooptical characteristics from the Strait of Gibraltar to the Dardanelles is considered and analyzed. The equation for the relationship between the asymmetry coefficient of the scattering phase function and the scattering coefficient in the Mediterranean Sea waters is obtained. Conclusions. The data characterizing spatial variability of the southern Mediterranean Sea water optical features in spring are obtained. The coefficients of beam attenuation and scattering in the surface waters decrease gradually from the western Mediterranean Sea to its eastern part. In the Aegean Sea near the Dardanelles, the Marmara Sea waters differing by their high coefficients of beam attenuation and scattering were observed. As for the basic parameters, the scattering phase functions in the Mediterranean Sea waters are similar to those in the Atlantic tropical waters. In the Mediterranean Sea waters as well as in the other water basins, the relationship between the asymmetry coefficient of the light scattering phase function and the scattering coefficient is observed; it is manifested in increase of the phase function asymmetry coefficient with the scattering coefficient.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43355610","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 : 2020-02-01DOI: 10.22449/1573-160x-2020-1-95-107
V. Bondur, V. Ivanov, V. E. Vorobiev, V. Dulov, V. Dolotov, V. Zamshin, S. Kondratiev, M. E. Lee, V. Malinovsky
Цель. Целью работы является создание и тестирование экспериментального образца системы наземно-космического мониторинга антропогенных воздействий на прибрежную зону Крымского п-ова с использованием спутниковых и контактных данных. Система предназначена для получения значимых параметров водной среды, необходимых для выявления источников антропогенных воздействий и выработки обоснованных рекомендаций по рациональному природопользованию и снижению уровня антропогенной нагрузки на морские экосистемы. Методы и результаты. В статье представлено общее описание структуры и использованных технических средств мониторинга с акцентом на наземный сегмент системы, реализованный на базе Морского гидрофизического института, приведен пример использования наземного сегмента для мониторинга прибрежных акваторий Крыма. Обсуждена концепция наземнокосмического мониторинга антропогенных воздействий на прибрежные акватории, лежащая в основе предлагаемой системы. Описан подспутниковый сегмент системы мониторинга, предназначенный для сбора, обработки и хранения информации, получаемой с контактных датчиков. Особое внимание уделено организации рабочего места оператора для оперативного анализа получаемых данных. Представлен опыт успешного применения системы мониторинга. Описана организация экспедиционных работ. Дан краткий обзор основных результатов, полученных за время тестирования системы мониторинга. Проиллюстрирован процесс комплексного анализа подспутниковых данных и многоспектральных космических изображений на примере обнаружения аварийного разрыва основной магистрали сброса сточных вод в г. Севастополе. Выводы. Разработана, реализована и протестирована система наземно-космического мониторинга антропогенных воздействий на прибрежную зону Крымского п-ова. Функционирование системы в 2015–2016 гг. показало ее высокую эффективность при выполнении оперативного комплексного анализа контактных и спутниковых данных, в особенности при выявлении аварийных ситуаций со сбросом сточных вод в море.
{"title":"Ground-to-Space Monitoring of Anthropogenic Impacts on the Coastal Zone of the Crimean Peninsula","authors":"V. Bondur, V. Ivanov, V. E. Vorobiev, V. Dulov, V. Dolotov, V. Zamshin, S. Kondratiev, M. E. Lee, V. Malinovsky","doi":"10.22449/1573-160x-2020-1-95-107","DOIUrl":"https://doi.org/10.22449/1573-160x-2020-1-95-107","url":null,"abstract":"Цель. Целью работы является создание и тестирование экспериментального образца системы наземно-космического мониторинга антропогенных воздействий на прибрежную зону Крымского п-ова с использованием спутниковых и контактных данных. Система предназначена для получения значимых параметров водной среды, необходимых для выявления источников антропогенных воздействий и выработки обоснованных рекомендаций по рациональному природопользованию и снижению уровня антропогенной нагрузки на морские экосистемы. Методы и результаты. В статье представлено общее описание структуры и использованных технических средств мониторинга с акцентом на наземный сегмент системы, реализованный на базе Морского гидрофизического института, приведен пример использования наземного сегмента для мониторинга прибрежных акваторий Крыма. Обсуждена концепция наземнокосмического мониторинга антропогенных воздействий на прибрежные акватории, лежащая в основе предлагаемой системы. Описан подспутниковый сегмент системы мониторинга, предназначенный для сбора, обработки и хранения информации, получаемой с контактных датчиков. Особое внимание уделено организации рабочего места оператора для оперативного анализа получаемых данных. Представлен опыт успешного применения системы мониторинга. Описана организация экспедиционных работ. Дан краткий обзор основных результатов, полученных за время тестирования системы мониторинга. Проиллюстрирован процесс комплексного анализа подспутниковых данных и многоспектральных космических изображений на примере обнаружения аварийного разрыва основной магистрали сброса сточных вод в г. Севастополе. Выводы. Разработана, реализована и протестирована система наземно-космического мониторинга антропогенных воздействий на прибрежную зону Крымского п-ова. Функционирование системы в 2015–2016 гг. показало ее высокую эффективность при выполнении оперативного комплексного анализа контактных и спутниковых данных, в особенности при выявлении аварийных ситуаций со сбросом сточных вод в море.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45276698","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 : 2020-02-01DOI: 10.22449/0233-7584-2020-1-88-102
I. Timchenko, E. M. Igumnova, S. V. Svishchev
Purpose. Complexity of biochemical processes in marine environment entails the problem of parameterizing their interactions in constructing the marine ecosystem mathematical models. The aim of the investigation is to simplify solution of this problem by applying the concept of the ecosystem stationary state and the hypothesis on balance of the processes’ mutual influence based on the matter balances of biochemical reactions in substance transformations. Methods and Results. To simplify the ecosystem model, applied is the method of the adaptive balance of causes which now is being developed by the authors. The method equations contain negative feedbacks between the ecosystem model variables and the velocities of their change. These feedbacks stabilize the equations’ solutions and make the model adaptive to the external effects on the ecosystem. The concept of the solutions’ convergence to the stationary state permitted to propose a simple methods (based on the normalized relationships between their average values) for estimating the coefficients of the processes’ mutual influences. To test these methods, the adaptive model of the Sevastopol Bay ecosystem was constructed. The data of multi-year observations of the chemical processes in the bay were used for assimilating the observations of the nitrate and ammonia concentrations in the model. The data were assimilated both through their reducing to the dimension and scales of the variability corresponding to the model variable, and their including to the right parts of the model equations as the additional sources and sinks. The numerical experiments carried out using the integral model of the Sevastopol Bay ecosystem showed that application of the normalized relationships between their average values as the estimates of the processes’ mutual influences permitted to reproduce the scenarios of all the processes in the ecosystem based on the limited observational data. The model response to the external effects at the constant and varying normalizing factors in the model coefficients is studied. It shows that the variable factors provide the model with higher sensitivity to the external effects. Conclusions. The adaptive models of marine ecosystems constructed by the method of the adaptive balance of causes provide fast solutions’ convergence to the stationary state. According to the laws of the matter balances’ conservation in the biochemical reactions in substance transformations, the adaptive model tends to establishing dynamical balances in the external and intra-system influences. Therefore the proposed methods of estimating the intra-system relationships’ coefficients in the marine ecosystem adaptive model permit to reconstruct the scenarios of those processes in which only their average values are known.
{"title":"Modeling of Intra-System Relationships in the Adaptive Model of the Marine Environment Biochemical Processes","authors":"I. Timchenko, E. M. Igumnova, S. V. Svishchev","doi":"10.22449/0233-7584-2020-1-88-102","DOIUrl":"https://doi.org/10.22449/0233-7584-2020-1-88-102","url":null,"abstract":"Purpose. Complexity of biochemical processes in marine environment entails the problem of parameterizing their interactions in constructing the marine ecosystem mathematical models. The aim of the investigation is to simplify solution of this problem by applying the concept of the ecosystem stationary state and the hypothesis on balance of the processes’ mutual influence based on the matter balances of biochemical reactions in substance transformations. Methods and Results. To simplify the ecosystem model, applied is the method of the adaptive balance of causes which now is being developed by the authors. The method equations contain negative feedbacks between the ecosystem model variables and the velocities of their change. These feedbacks stabilize the equations’ solutions and make the model adaptive to the external effects on the ecosystem. The concept of the solutions’ convergence to the stationary state permitted to propose a simple methods (based on the normalized relationships between their average values) for estimating the coefficients of the processes’ mutual influences. To test these methods, the adaptive model of the Sevastopol Bay ecosystem was constructed. The data of multi-year observations of the chemical processes in the bay were used for assimilating the observations of the nitrate and ammonia concentrations in the model. The data were assimilated both through their reducing to the dimension and scales of the variability corresponding to the model variable, and their including to the right parts of the model equations as the additional sources and sinks. The numerical experiments carried out using the integral model of the Sevastopol Bay ecosystem showed that application of the normalized relationships between their average values as the estimates of the processes’ mutual influences permitted to reproduce the scenarios of all the processes in the ecosystem based on the limited observational data. The model response to the external effects at the constant and varying normalizing factors in the model coefficients is studied. It shows that the variable factors provide the model with higher sensitivity to the external effects. Conclusions. The adaptive models of marine ecosystems constructed by the method of the adaptive balance of causes provide fast solutions’ convergence to the stationary state. According to the laws of the matter balances’ conservation in the biochemical reactions in substance transformations, the adaptive model tends to establishing dynamical balances in the external and intra-system influences. Therefore the proposed methods of estimating the intra-system relationships’ coefficients in the marine ecosystem adaptive model permit to reconstruct the scenarios of those processes in which only their average values are known.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43380867","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 : 2020-02-01DOI: 10.22449/0233-7584-2020-1-5-19
A. Slepyshev, A. Nosova
Purpose. The aim is to study the mechanism of formation of a vertical fine structure due to the mass vertical transfer by the internal waves taking into account turbulent viscosity and diffusion as well as to investigate influence of the critical layers on the dispersion curves of internal waves. Methods and Results. In the Boussinesq approximation, the free inertia-gravity internal waves in a vertically inhomogeneous flow are considered with the regard for the horizontal turbulent viscosity and diffusion. The equation for the amplitude of vertical velocity of the internal waves contains a small parameter (in the dimensionless variables) proportional to the value of the horizontal turbulent viscosity. The solution of this equation is realized in a form of the asymptotic series of this parameter. In the zero approximation, the second-order homogeneous boundary value problem determined the vertical structure mode is solved numerically by the implicit third-order accuracy Adams scheme for real profiles of the Brent-Väisälä frequency and the current velocity. At the fixed wave frequency, the wave number is determined by the shooting method. In the first order with respect to the indicated parameter, the semi-homogeneous boundary value problem is also solved numerically according to the implicit Adams scheme of the third order of accuracy. A unique solution is found which is orthogonal to the solution of the corresponding homogeneous boundary value problem. The condition of this boundary value problem solvability yields the wave attenuation decrement. The dispersion curves of the first two modes are cut off in the lowfrequency region (the second mode is at a higher frequency), that is due to influence of the critical layers, where the wave frequency with the Doppler shift is inertial. It is shown that the mass vertical wave flux differs from zero and leads to correction (not oscillating on the wave time scale) of the average density, i. e. the internal wave generate fine structure that is of an irreversible character. Conclusions. When the horizontal turbulent viscosity and diffusion are taken into consideration, the mass vertical wave flux differs from zero and leads to generation of the vertical fine structure. The mass wave flux exceeds the turbulent one. The vertical scales of the generated vertical fine structure correspond to the actually observed ones.
{"title":"Generation of Vertical Fine Structure by the Internal Waves with the Regard for Turbulent Viscosity and Diffusion","authors":"A. Slepyshev, A. Nosova","doi":"10.22449/0233-7584-2020-1-5-19","DOIUrl":"https://doi.org/10.22449/0233-7584-2020-1-5-19","url":null,"abstract":"Purpose. The aim is to study the mechanism of formation of a vertical fine structure due to the mass vertical transfer by the internal waves taking into account turbulent viscosity and diffusion as well as to investigate influence of the critical layers on the dispersion curves of internal waves. Methods and Results. In the Boussinesq approximation, the free inertia-gravity internal waves in a vertically inhomogeneous flow are considered with the regard for the horizontal turbulent viscosity and diffusion. The equation for the amplitude of vertical velocity of the internal waves contains a small parameter (in the dimensionless variables) proportional to the value of the horizontal turbulent viscosity. The solution of this equation is realized in a form of the asymptotic series of this parameter. In the zero approximation, the second-order homogeneous boundary value problem determined the vertical structure mode is solved numerically by the implicit third-order accuracy Adams scheme for real profiles of the Brent-Väisälä frequency and the current velocity. At the fixed wave frequency, the wave number is determined by the shooting method. In the first order with respect to the indicated parameter, the semi-homogeneous boundary value problem is also solved numerically according to the implicit Adams scheme of the third order of accuracy. A unique solution is found which is orthogonal to the solution of the corresponding homogeneous boundary value problem. The condition of this boundary value problem solvability yields the wave attenuation decrement. The dispersion curves of the first two modes are cut off in the lowfrequency region (the second mode is at a higher frequency), that is due to influence of the critical layers, where the wave frequency with the Doppler shift is inertial. It is shown that the mass vertical wave flux differs from zero and leads to correction (not oscillating on the wave time scale) of the average density, i. e. the internal wave generate fine structure that is of an irreversible character. Conclusions. When the horizontal turbulent viscosity and diffusion are taken into consideration, the mass vertical wave flux differs from zero and leads to generation of the vertical fine structure. The mass wave flux exceeds the turbulent one. The vertical scales of the generated vertical fine structure correspond to the actually observed ones.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42461186","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 : 2020-02-01DOI: 10.22449/1573-160x-2020-1-69-80
A. P. Tolstosheev, S. Motyzhev, E. Lunev
{"title":"Results of Long-Term Monitoring of the Shelf Water Vertical Thermal Struture at the Black Sea Hydrophysical Polygon of RAS","authors":"A. P. Tolstosheev, S. Motyzhev, E. Lunev","doi":"10.22449/1573-160x-2020-1-69-80","DOIUrl":"https://doi.org/10.22449/1573-160x-2020-1-69-80","url":null,"abstract":"","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43900971","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 : 2020-02-01DOI: 10.22449/0233-7584-2020-1-75-87
A. P. Tolstosheev, S. Motyzhev, E. Lunev
Purpose. The geographical and climatic features of the Crimean Southern coast condition significant dynamic activity of the water thermal structure. Studies of the temperature vertical variability in the absence of the tides’ dominant affect, permit to specify the upwelling structure and dynamics as well as the characteristics of waves of various origin. Such hardly-forecasted processes, the time scales of which constitute from a few minutes to several days can be revealed and registered only by long-term continuous observations. The aim of the study is to analyze the results of long-term monitoring of the thermal processes in the coastal zone near the Crimean Southern coast. It was performed at the Black Sea hydrophysical scientific polygon. Methods and Results. In December, 2012 the observation system for operational control of the water temperature vertical distribution was installed at the stationary platform located in the coastal zone of the Black Sea (the Blue Bay) at a distance of ~450 m from the coast. The sea depth under the platform was ~30 m. Digital temperature sensors having precision better than 0.1 °C were installed with 1.5 m intervals in the temperature string of the system. The profiling period was 60 s. The 6.5 year-long experiment with the observation system provided statistically significant and duration-unique serious of data on variability of the thermal processes in the sea coastal region. By early April 2019, the total duration of the system productive functioning was ~900 days. During this period, more than 1300000 temperature profiles were obtained. Based on the data obtained in 2013, the estimates of a seasonal cycle of the temperature synoptic variability are represented. The upwelling events not related to the wind impact are considered. Conclusions. The long-term data series resulted from the multi-year experiment permit not only to specify, but also to change some of the existing ideas of the thermal processes’ evolution features in shelf zone of the Black Sea. Noted is the expediency of applying the observation system as a segment of the constantly operating network at the coastal polygons for performing hydrophysical measurements in the Black Sea.
{"title":"Results of Long-Term Monitoring of the Shelf Water Vertical Thermal Structure at the Black Sea Hydrophysical Polygon of RAS","authors":"A. P. Tolstosheev, S. Motyzhev, E. Lunev","doi":"10.22449/0233-7584-2020-1-75-87","DOIUrl":"https://doi.org/10.22449/0233-7584-2020-1-75-87","url":null,"abstract":"Purpose. The geographical and climatic features of the Crimean Southern coast condition significant dynamic activity of the water thermal structure. Studies of the temperature vertical variability in the absence of the tides’ dominant affect, permit to specify the upwelling structure and dynamics as well as the characteristics of waves of various origin. Such hardly-forecasted processes, the time scales of which constitute from a few minutes to several days can be revealed and registered only by long-term continuous observations. The aim of the study is to analyze the results of long-term monitoring of the thermal processes in the coastal zone near the Crimean Southern coast. It was performed at the Black Sea hydrophysical scientific polygon. Methods and Results. In December, 2012 the observation system for operational control of the water temperature vertical distribution was installed at the stationary platform located in the coastal zone of the Black Sea (the Blue Bay) at a distance of ~450 m from the coast. The sea depth under the platform was ~30 m. Digital temperature sensors having precision better than 0.1 °C were installed with 1.5 m intervals in the temperature string of the system. The profiling period was 60 s. The 6.5 year-long experiment with the observation system provided statistically significant and duration-unique serious of data on variability of the thermal processes in the sea coastal region. By early April 2019, the total duration of the system productive functioning was ~900 days. During this period, more than 1300000 temperature profiles were obtained. Based on the data obtained in 2013, the estimates of a seasonal cycle of the temperature synoptic variability are represented. The upwelling events not related to the wind impact are considered. Conclusions. The long-term data series resulted from the multi-year experiment permit not only to specify, but also to change some of the existing ideas of the thermal processes’ evolution features in shelf zone of the Black Sea. Noted is the expediency of applying the observation system as a segment of the constantly operating network at the coastal polygons for performing hydrophysical measurements in the Black Sea.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45038579","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 : 2020-02-01DOI: 10.22449/0233-7584-2020-1-20-30
А. Bukatov, N. M. Solovei, E. A. Pavlenko
Purpose. The aim of the paper is to investigate spatial-temporal dependences of the dispersion features of short-period free internal waves on the density field vertical structure in the Barents and Kara seas. Methods and Results. Based on the linearized equations of motion of the ideal incompressible and continuously stratified fluid, the dispersion features of free internal waves in the Barents and Kara seas were studied. Solution of the main boundary problem of the Sturm-Liouville type made it possible to obtain the own frequencies of five lowest modes and the own period of the internal waves’ first mode. To calculate the density field, the World Ocean Atlas 2013 reanalysis data on temperature and salinity for 1955–2012 with resolution 0.25° × 0.25° were applied. The relation between the dispersion features of free internal waves and the density field vertical structure was analyzed, and dispersion characteristics of theinternal waves in the Barents and Kara seas were compared. Conclusions. During the months when the density gradients are maximal, the internal waves of the highest frequency and the shortest period are observed. Among the intra-year maximums of the buoyancy depth-averaged frequency, the highest values (≈ 0.02 s) are observed in the Barents Sea in July and August, and those of the Kara Sea – in July–September (≈ 0.055 s) and in November (≈ 0.058 s). In the same months, noted are the maximum values of the averaged natural frequencies and the minimum values of the averaged own period of the internal waves. Thus, for the wavelength 1000 m, the highest averaged own frequency and the smallest averaged own period of the first mode in the Barents Sea constitute 0.0025 s and 45 min., and those in the Kara Sea – 0.0038 s and 30 min, respectively.
{"title":"Estimation of the Relation between the Dispersion Features of Free Internal Waves and the Density Field Vertical Structure in the Barents and Kara Seas","authors":"А. Bukatov, N. M. Solovei, E. A. Pavlenko","doi":"10.22449/0233-7584-2020-1-20-30","DOIUrl":"https://doi.org/10.22449/0233-7584-2020-1-20-30","url":null,"abstract":"Purpose. The aim of the paper is to investigate spatial-temporal dependences of the dispersion features of short-period free internal waves on the density field vertical structure in the Barents and Kara seas. Methods and Results. Based on the linearized equations of motion of the ideal incompressible and continuously stratified fluid, the dispersion features of free internal waves in the Barents and Kara seas were studied. Solution of the main boundary problem of the Sturm-Liouville type made it possible to obtain the own frequencies of five lowest modes and the own period of the internal waves’ first mode. To calculate the density field, the World Ocean Atlas 2013 reanalysis data on temperature and salinity for 1955–2012 with resolution 0.25° × 0.25° were applied. The relation between the dispersion features of free internal waves and the density field vertical structure was analyzed, and dispersion characteristics of theinternal waves in the Barents and Kara seas were compared. Conclusions. During the months when the density gradients are maximal, the internal waves of the highest frequency and the shortest period are observed. Among the intra-year maximums of the buoyancy depth-averaged frequency, the highest values (≈ 0.02 s) are observed in the Barents Sea in July and August, and those of the Kara Sea – in July–September (≈ 0.055 s) and in November (≈ 0.058 s). In the same months, noted are the maximum values of the averaged natural frequencies and the minimum values of the averaged own period of the internal waves. Thus, for the wavelength 1000 m, the highest averaged own frequency and the smallest averaged own period of the first mode in the Barents Sea constitute 0.0025 s and 45 min., and those in the Kara Sea – 0.0038 s and 30 min, respectively.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43620146","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: 10.22449/0233-7584-2019-6-600-620
V. M. Goloviznin, Pavel A. Maiorov, Petr A. Maiorov, A. V. Solovjov
Purpose. The present article is devoted to describing a new method of numerical solution for hydrostatic approximation of incompressible hydrodynamic problems with free surfaces and variable density. Methods and Results. The algorithm is based on the hyperbolic decomposition method, i. e. representation of a multilayer model as a sum of the one-layer models interacting by means of the reaction forces through the layers’ interfaces. The forces acting on the upper and lower interfaces of each layer are interpreted as the external ones which do not break hyperbolicity of the equations system for each layer. The explicit CABARET scheme is used to solve a system of hyperbolic equations with variable density in each layer. The scheme is of the second approximation order and the time reversibility. Its feature consists in the increased number of freedom degrees: along with the conservative-type variables referred to the centers of the calculated cells, applied are the flux-type variables related to the middle of the vertical edges of these cells. The system of the multilayer shallow water equations is not unconditionally hyperbolic, and in case hyperbolicity is lost, it becomes ill-posed. Hyperbolic decomposition does not remove incorrectness of the original system of the multilayer shallow water equations. To regularize the numerical solution, the following set of tools is propose: filtration of the flow variables at each time step; super-implicit approximation of the pressure gradient; linear artificial viscosity and transition to the Euler-Lagrangian (SEL) variables that leads to the mass and momentum exchange between the layers. Such transition to the SEL variables is the basic tool for stabilizing numerical solution at large times. The rest of the tricks are the auxiliary ones and used for fine tuning. Conclusions. It is shown that regularizing and guaranteeing the problems’ stability requires not only reconstruction of the computational grid at each time step, but also application of the flow-type variables’ filtering and the artificial viscosity simulating turbulent mixing.
{"title":"New Numerical Algorithm for the Multi-Layer Shallow Water Equations Based on the Hyperbolic Decomposition and the CABARET Scheme","authors":"V. M. Goloviznin, Pavel A. Maiorov, Petr A. Maiorov, A. V. Solovjov","doi":"10.22449/0233-7584-2019-6-600-620","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-6-600-620","url":null,"abstract":"Purpose. The present article is devoted to describing a new method of numerical solution for hydrostatic approximation of incompressible hydrodynamic problems with free surfaces and variable density. Methods and Results. The algorithm is based on the hyperbolic decomposition method, i. e. representation of a multilayer model as a sum of the one-layer models interacting by means of the reaction forces through the layers’ interfaces. The forces acting on the upper and lower interfaces of each layer are interpreted as the external ones which do not break hyperbolicity of the equations system for each layer. The explicit CABARET scheme is used to solve a system of hyperbolic equations with variable density in each layer. The scheme is of the second approximation order and the time reversibility. Its feature consists in the increased number of freedom degrees: along with the conservative-type variables referred to the centers of the calculated cells, applied are the flux-type variables related to the middle of the vertical edges of these cells. The system of the multilayer shallow water equations is not unconditionally hyperbolic, and in case hyperbolicity is lost, it becomes ill-posed. Hyperbolic decomposition does not remove incorrectness of the original system of the multilayer shallow water equations. To regularize the numerical solution, the following set of tools is propose: filtration of the flow variables at each time step; super-implicit approximation of the pressure gradient; linear artificial viscosity and transition to the Euler-Lagrangian (SEL) variables that leads to the mass and momentum exchange between the layers. Such transition to the SEL variables is the basic tool for stabilizing numerical solution at large times. The rest of the tricks are the auxiliary ones and used for fine tuning. Conclusions. It is shown that regularizing and guaranteeing the problems’ stability requires not only reconstruction of the computational grid at each time step, but also application of the flow-type variables’ filtering and the artificial viscosity simulating turbulent mixing.","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":"47624412","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: 10.22449/0233-7584-2019-6-633-645
G. Dyakonov, R. Ibrayev
Purpose. The paper is aimed at studying water exchange between the Middle and South Caspian, at assessing its intensity, spatial-temporal structure and variability. Methods and Results. The study includes the numerical model of the Caspian Sea general circulation; it is of sufficiently high resolution for reproducing mesoscale structure of the currents – 2 km. Due to the model, the Caspian Sea circulation in 2003 was reconstructed and the basic characteristics of water transfer between the Middle and the South Caspian were calculated. This specific year was chosen since in all its months, the wind fields in the Middle and South Caspian water areas were in good agreement with the average climatic ones. The simulated structure of the currents over the Apsheron Sill represents the following pattern: the northward currents are most often formed over the eastern shelf slopes, and the southward ones – over the western shelf slope. The latter are usually more intense and regular. From mid-July to October, the easterly winds regularly occur over the Caspian Sea strengthening the northward currents, which, in their turn, transfer relatively salty and warm South Caspian waters to the Middle Caspian along the eastern coast. A fairly stable southward stream resulted from the density gradient between the cold Middle and the warm South Caspian, is located along the western shelf slope at the depths 100–150 m. On the whole, the water flow above the sill is directed from north to south. At that the southward flows are distributed rather evenly throughout the year, whereas the major part of the northward currents’ flow is observed from late July to December. Conclusions. Since the South Caspian waters on all the depths are warmer and more salty than those in the Middle, water exchange between the two basins in course of the whole year, contributes to increase both of temperature and salinity in the Middle Caspian, and to their decrease in the South Caspian. The current-originated salt flows in the region are sufficient to make salinity grow in the Middle Caspian upper layer by 0.5 psu within 100 days, at that the corresponding temperature increase does not exceed 0.01–0.03 °C per day. The reverse southward currents transfer relatively fresh water to the South Caspian that lowers salinity of its upper layer by 0.2 psu per month. However, such intense intrusions are noted only in March and December. The impact of these currents on the South Caspian heat balance is more uniform throughout the year and does not exceed 0.17 °C/day.
{"title":"Dynamics of the Caspian Sea Waters over the Apsheron Sill in 2003","authors":"G. Dyakonov, R. Ibrayev","doi":"10.22449/0233-7584-2019-6-633-645","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-6-633-645","url":null,"abstract":"Purpose. The paper is aimed at studying water exchange between the Middle and South Caspian, at assessing its intensity, spatial-temporal structure and variability. Methods and Results. The study includes the numerical model of the Caspian Sea general circulation; it is of sufficiently high resolution for reproducing mesoscale structure of the currents – 2 km. Due to the model, the Caspian Sea circulation in 2003 was reconstructed and the basic characteristics of water transfer between the Middle and the South Caspian were calculated. This specific year was chosen since in all its months, the wind fields in the Middle and South Caspian water areas were in good agreement with the average climatic ones. The simulated structure of the currents over the Apsheron Sill represents the following pattern: the northward currents are most often formed over the eastern shelf slopes, and the southward ones – over the western shelf slope. The latter are usually more intense and regular. From mid-July to October, the easterly winds regularly occur over the Caspian Sea strengthening the northward currents, which, in their turn, transfer relatively salty and warm South Caspian waters to the Middle Caspian along the eastern coast. A fairly stable southward stream resulted from the density gradient between the cold Middle and the warm South Caspian, is located along the western shelf slope at the depths 100–150 m. On the whole, the water flow above the sill is directed from north to south. At that the southward flows are distributed rather evenly throughout the year, whereas the major part of the northward currents’ flow is observed from late July to December. Conclusions. Since the South Caspian waters on all the depths are warmer and more salty than those in the Middle, water exchange between the two basins in course of the whole year, contributes to increase both of temperature and salinity in the Middle Caspian, and to their decrease in the South Caspian. The current-originated salt flows in the region are sufficient to make salinity grow in the Middle Caspian upper layer by 0.5 psu within 100 days, at that the corresponding temperature increase does not exceed 0.01–0.03 °C per day. The reverse southward currents transfer relatively fresh water to the South Caspian that lowers salinity of its upper layer by 0.2 psu per month. However, such intense intrusions are noted only in March and December. The impact of these currents on the South Caspian heat balance is more uniform throughout the year and does not exceed 0.17 °C/day.","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":"45649736","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: 10.22449/0233-7584-2019-6-646-661
A. Mizyuk, M. V. Senderov, G. Korotaev
Purpose. At present the process of formation of haline stratification in the Black Sea is poorly studied. The current state of the basin is considered to be close to equilibrium. However, having been analyzed, the long-term observations testify to a tendency towards desalination of the sea surface layer and salination of the deep waters. The goal of the study is to obtain a complete pattern of the haline stratification formation in the basin and the characteristic time scales of its long-term climatic evolution. Methods and Results. Numerical calculations of the Black Sea circulation which is formed being influenced by water exchange through the Bosporus, river runoff, precipitation and evaporation, are compared with the laboratory simulation results obtained previously using the NEMO model. It is shown that the time period of formation of the upper and lower Bosporus currents is of a characteristic time scale 20 years. Relatively short period of adaptation of the Bosporus water exchange to the external conditions testifies that on the climatic scale, the strait should be in a quasi-equilibrium state. The results of the numerical experiments also show that, against the background of the initially preset constant salinity of the Black Sea, the vertical haline stratification is formed rather rapidly due to the fact that the upper forty-meter layer is desalinated by the river runoffs. This leads to formation of a halocline in the 10–40 m layer. In the deeper layers, salinity increases slowly owing to the Marmora Sea water inflow. Each of the calculations shows that intense desalination of the surface layer lasts 70–80 years, whereupon its salinity grows slowly. Conclusions. As a result, the characteristic adaptation period of the basin stratification to the changes in the external factors constitutes 70–100 years. After the equilibrium regime is settled, slow quasi-stationary evolution of the basin fields takes place. Analysis of the obtained results enabled us to deduce the equations for describing slow evolution of the haline stratification.
{"title":"Basic Regularities of the Haline Stratification Long-Term Evolution in the Black Sea","authors":"A. Mizyuk, M. V. Senderov, G. Korotaev","doi":"10.22449/0233-7584-2019-6-646-661","DOIUrl":"https://doi.org/10.22449/0233-7584-2019-6-646-661","url":null,"abstract":"Purpose. At present the process of formation of haline stratification in the Black Sea is poorly studied. The current state of the basin is considered to be close to equilibrium. However, having been analyzed, the long-term observations testify to a tendency towards desalination of the sea surface layer and salination of the deep waters. The goal of the study is to obtain a complete pattern of the haline stratification formation in the basin and the characteristic time scales of its long-term climatic evolution. Methods and Results. Numerical calculations of the Black Sea circulation which is formed being influenced by water exchange through the Bosporus, river runoff, precipitation and evaporation, are compared with the laboratory simulation results obtained previously using the NEMO model. It is shown that the time period of formation of the upper and lower Bosporus currents is of a characteristic time scale 20 years. Relatively short period of adaptation of the Bosporus water exchange to the external conditions testifies that on the climatic scale, the strait should be in a quasi-equilibrium state. The results of the numerical experiments also show that, against the background of the initially preset constant salinity of the Black Sea, the vertical haline stratification is formed rather rapidly due to the fact that the upper forty-meter layer is desalinated by the river runoffs. This leads to formation of a halocline in the 10–40 m layer. In the deeper layers, salinity increases slowly owing to the Marmora Sea water inflow. Each of the calculations shows that intense desalination of the surface layer lasts 70–80 years, whereupon its salinity grows slowly. Conclusions. As a result, the characteristic adaptation period of the basin stratification to the changes in the external factors constitutes 70–100 years. After the equilibrium regime is settled, slow quasi-stationary evolution of the basin fields takes place. Analysis of the obtained results enabled us to deduce the equations for describing slow evolution of the haline stratification.","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":"45763654","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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