Marine Hydrophysical Institute Research Articles

Sea level oscillations spectra of a shallow coastal bay: Cost-effective measurements and numerical modelling in Kruglaya Bay

Seiches are long standing waves typical of enclosed and semi-enclosed basins. It is shown that they can be generated in bays by long-period waves coming from open sea through an entry. An interaction between adjacent bays may extend the number of seiche modes in these bays. Kruglaya Bay is widely used for recreational purposes. We measured sea level variations in Kruglaya Bay in August-October, 2022 by means of a cost-effective and robust autonomous sea-level recorder designed and assembled in Marine Hydrophysical Institute. Measurements were conducted based on an ultra-sound JSN-SR04T sensor. SWASH, a numerical high-resolution model, was used to simulate dissipating free oscillations in a system of connected shallow semi-enclosed bays initiated by long waves incoming from the open sea. A spectral analysis of measured sea level fluctuations was used to identify resonant periods of local seiches in Kruglaya Bay. Estimate periods of oscillations that correspond to incoming long waves from the neighbouring bays were obtained using the results of mathematical modeling. The performed wavelet analysis permitted to identify situations when local resonant oscillations were initiated before wind intensification (which manifested as an increase in energy at the high-frequency part of the spectrum). An intense fundamental mode (also known as the ‘Helmholtz mode’ of a semi-enclosed oscillating basin) of Kruglaya Bay (period around 14 min) was identified both in measurements and the numerical simulation. The power spectra of the sea level oscillations in Kruglaya Bay also showed significant peaks at the periods of fundamental modes of the neighbouring bays. Besides, periods of the Black Sea seiches (1.25 h and 2.5 h) were identified from the observations.

Analysis of Seasonal Energy Characteristics of the Marmara Sea Upper Layer Dynamics

Purpose. The aim of the work is to assess the role of the basic forces in formation of the dynamic structures of the upper layer in the Marmara Sea in different hydrological seasons. Methods and Results. The numerical model developed in Marine Hydrophysical Institute, Russian Academy of Sciences, was used to calculate the hydrodynamic and energy characteristics of the sea circulation. The horizontal spatial resolution was 1.22 × 0.83 km, 18 horizons were used vertically, and the time step was 0.5 min. The characteristics of the waters inflowing through the Bosporus and Dardanelles straits corresponded to the available observational data. On the sea surface, the daily average fields of tangential wind stress, heat fluxes, precipitation and evaporation for 2008 were preset; these parameters were calculated using the regional atmospheric model MM5. Spatial distributions of the vortex structures and the corresponding energy flows in the upper sea layer for different seasons were considered. Having been analyzed, the average seasonal spatial distributions of the current velocity fields and the components of the kinetic energy budget showed that during the year, the vortices in the upper sea layer were formed mainly by two mechanisms. In the central part of the sea, generation of a large-scale anticyclone and its seasonal variability are basically conditioned by the wind forcing, whereas formation and evolution of coastal cyclonic eddies are caused by the buoyancy force. In the fields where the buoyancy, pressure and friction forcing takes place, the zones of local extremes are distinguished. Two of them are the areas of water inflow through the Bosphorus and Dardanelles straits. The strongest variability is observed in the Bosporus region that is certainly conditioned by the fact that the inflowing Black Sea waters have a decisive influence on seasonal nature of the Marmara Sea circulation. The extreme values in the other zones are the result of the coastline structure heterogeneities, that leads to formation of the coastal eddies, the energy source for which is the available potential energy. Conclusions. Analysis of the results of the performed numerical experiment makes it possible to conclude that in the upper layer of the Marmara Sea, formation and variability of the central anticyclone are conditioned by the wind forcing, while those of the coastal cyclones – by the buoyancy effect.

Preface

The origins of the Conference start from 1970 in the Soviet Union, Novosibirsk. It was organized by Kutateladze Institute of Thermophysics SB RAS. The name of the conference was «Actual problems of thermophysics and physical hydrodynamics». The conference has been organized under this name up to 2015. The conference chairs were academicians of RAS V. E. Nakoryakov, S. V. Alekseenko and D. M. Marckovich. Peer reviewed proceedings of the conference have been published in the format of printed books. In 2016 the conference is reorganized in a new format with a shorter name: «Thermophysics and physical hydrodynamics» (TPH2021). The proceedings of the renewal Conference were published in the Journal of physics: conference series. The conference was held jointly with the scientific youth school «Thermophysics and Physical Hydrodynamics: Modern Challenges» (TPHMC2021). The scientific school is a lecture intensive. Invited lecturers – famous scientists and specialists from all over Russia talk about the achievements of their groups, teams, organizations. The subsequent work of young scientists in the sections of TPH2021 provides an opportunity to look at the challenges facing science in detail, ask questions, and get answers that can give an impetus to the development of their own research.The conference takes place in Sevastopol, a beautiful and honor city in Crimea on the bank of the Black Sea. Ministry of Science and Higher Education of the Russian Federation, Siberian Branch of the Russian Academy of Sciences, National Committee on Heat and Mass Transfer RAS, Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk State University, Novosibirsk State Technical University, Marine Hydrophysical Institute RAS, and Sevastopol State University are among other conference organizers besides Kutateladze Institute of thermophysics. The present Conference covers the following topics: heat transfer and hydrodynamics in single phase flows, hydrodynamics and heat and mass transfer in multiphase flows, phase transitions, reacting flow dynamics, detonation processes, numerical methods in thermophysics and physical hydrodynamics, techniques of thermophysics and hydrodynamics experiment, thermophysical properties of substances, heat and mass transfer on micro- and nanoscales, electrophysical phenomena in gaseous and liquid media, heat transfer and hydrodynamics in industrial processes and environment protection.There are more than 180 participants. The proceedings contain 137 papers grouped by topic. The scientific committee appreciates the enormous work of the editorial board and reviewers in the preparation of this volume. We would like to express our sincere thanks to all authors for their research contributions, and to organizers of the conference for their valuable spadework, especially to specialists of MKS LLC.

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

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

Analiz sezonnykh energeticheskikh kharakteristik dinamiki verkhnego sloya vod Mramornogo morya

Purpose. The aim of the work is to assess the role of the basic forces in formation of the dynamic structures of the upper layer in the Marmara Sea in different hydrological seasons. Methods and Results. The numerical model developed in Marine Hydrophysical Institute, Russian Academy of Sciences, was used to calculate the hydrodynamic and energy characteristics of the sea circulation. The horizontal spatial resolution was 1.22 × 0.83 km, 18 horizons were used vertically, and the time step was 0.5 min. The characteristics of the waters inflowing through the Bosporus and Dardanelles straits corresponded to the available observational data. On the sea surface, the daily average fields of tangential wind stress, heat fluxes, precipitation and evaporation for 2008 were preset; these parameters were calculated using the regional atmospheric model MM5. Spatial distributions of the vortex structures and the corresponding energy flows in the upper sea layer for different seasons were considered. Having been analyzed, the average seasonal spatial distributions of the current velocity fields and the components of the kinetic energy budget showed that during the year, the vortices in the upper sea layer were formed mainly by two mechanisms. In the central part of the sea, generation of a large-scale anticyclone and its seasonal variability are basically conditioned by the wind forcing, whereas formation and evolution of coastal cyclonic eddies are caused by the buoyancy force. In the fields where the buoyancy, pressure and friction forcing takes place, the zones of local extremes are distinguished. Two of them are the areas of water inflow through the Bosphorus and Dardanelles straits. The strongest variability is observed in the Bosporus region that is certainly conditioned by the fact that the inflowing Black Sea waters have a decisive influence on seasonal nature of the Marmara Sea circulation. The extreme values in the other zones are the result of the coastline structure heterogeneities, that leads to formation of the coastal eddies, the energy source for which is the available potential energy. Conclusions. Analysis of the results of the performed numerical experiment makes it possible to conclude that in the upper layer of the Marmara Sea, formation and variability of the central anticyclone are conditioned by the wind forcing, while those of the coastal cyclones – by the buoyancy effect

Vertikal'noye raspredeleniye form fosfora v Chernom more po ekspeditsionnym dannym 2016–2019 godov

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

Assessment of the Black Sea Temperature and Salinity Climatic Fields for the Recent Climatological Period (1991–2020)

Purpose. The purpose of the study is to assess the coefficient of vertical turbulent exchange for different layers of the Black Sea basin based on the experimental data on microstructure of the physical fields obtained for the period 2004–2019 in the Black Sea and using the semi-empirical models. Methods and Results. New array of the temperature and salinity climatic fields was assessed by the results of numerical experiments. In the experiment, annual variation of the Black Sea hydrophysical parameters was reconstructed by the numerical model. Modeling included the scheme of assimilating the data of the climatic temperature and salinity array assessed. In contrast to the averaged data of the field observations, the modeled fields are compliant with equations of motion. Besides the temperature and salinity three-dimensional fields, the three-dimensional climatic fields of the Black Sea currents were also reconstructed for each day of a climatic year that is quite impossible using the observational data only. Spatial-temporal variability of the modeled three-dimensional fields was analyzed. The integral characteristics of the Black Sea water dynamics for the recent 30-year climatic period were studied and compared with the analogous ones for the previous century. Simulation was carried out by three-dimensional non-linear model of the Black Sea dynamics developed in Marine Hydrophysical Institute. The horizontal resolution of the model was 5 km, and the EMODNet bathymetry was used. The performed calculations showed that the increased spatial resolution of the temperature and salinity climatic array for the recent period made it possible to reconstruct the dynamics of the Black Sea in all layers in more detail. At the same time, significant small-scale variability of salinity fields was revealed. It was most pronounced at the deep-water horizons. Conclusions. Modeling using a new array of thermohaline fields revealed an increase in the integral temperature of the upper mixed layer in comparison with the experiment with assimilation of the previous version of the climatic array. At that, thinning and «break» of the cold intermediate layer found in the central part of the sea, indicates warming of the sea upper layer during the last 30 years. The highest noise detected at the deep-water horizons in the modeled salinity fields is related to quantity and quality of the salinity data resulted from the field observations. Taking into account insufficient calibration facilities for measuring seawater electrical conductivity, the next version of climatic TS-array requires a more strict procedure for verifying and processing the observation data obtained in the deep-sea layers.

Otsenka klimaticheskikh poley temperatury i solenosti vod Chernogo morya dlya sovremennogo perioda (1991–2020)

Purpose. The study is aimed at assessing a new climatic array of the Black Sea temperature and salinity calculated using hydrological observations for the standard (according to the World Meteorological Organization definition) 30-year climatological period 1991–2020. Methods and Results. New array of the temperature and salinity climatic fields was assessed based on analyzing the results of numerical experiments. In the experiment, annual variation of the Black Sea hydrophysical parameters was reproduced by the numerical model. Modeling included the scheme of assimilating the data of the climatic temperature and salinity array assessed. In contrast to the averaged data of the field observations, the model fields were matched from the viewpoint of the motion equations. Besides the temperature and salinity three-dimensional fields, the three-dimensional climatic fields of the Black Sea currents were also reproduced for each day of a climatic year that is quite impossible using the instrumental measurements data only. Spatial-temporal variability of the modeled three-dimensional fields was analyzed. The integral characteristics of the Black Sea water dynamics for the recent 30-year climatic period were studied and compared with the analogous ones for the previous century. Simulation was performed at the grid with the 5 km horizontal resolution using the EMODNet bathymetry by means of the three-dimensional non-linear model of the Black Sea dynamics developed in Marine Hydrophysical Institute. Having been analyzed, the performed calculations showed that the increased spatial resolution of the temperature and salinity climatic array for the recent period made it possible to reproduce dynamics in all the layers of the Black Sea waters in more details. At the same time, a significant small-scale variability, most pronounced at the deep-water horizons, was present in the salinity fields. Conclusions. As compared to the experiment with assimilation of the previous version of the climatic array, the modeling based on the new array of the thermohaline fields revealed increase in the integral temperature of the upper mixed layer. At that, thinning and «break» of the cold intermediate layer found in the central part of the sea, indicates warming of the sea upper layer during the last 30 years. The highest noisiness detected at the deep-water horizons in the modeled salinity fields is related to quantity and quality of the salinity data resulted from the field observations. Taking into account insufficient metrological facilities for measuring seawater electrical conductivity, the next version of climatic array requires a more strict procedure for verifying and processing the observation data obtained in the deep-sea layers.

Investigation of Airborne Particulate Matter in the Atmosphere of the Black Sea Coastal Zone Based on the Measured and Satellite Data

Purpose. One of the most pressing problems of large cities is air pollution resulting from presence of various large and fine particles in the air. These micro-particles can be transported by the air currents over considerable distances, as well as coagulate various substances also present in the atmosphere. The purpose of the work is to study the content of particulate matter of 2.5 and 10 microns (PM2.5 and PM10) in the atmosphere of Sevastopol, as well as the processes affecting their concentration. Methods and Results. During the period from February to June, 2020, the scientists of Marine Hydrophysical Institute (MHI), RAS measured mass concentration of PM2.5 and PM10 in Sevastopol using the “Atmas” dust analyzer. A total of 180 measurements of the micro-particle concentrations in the air of Sevastopol were done, and 60 values of the PM2.5 and PM10 daily average concentrations were obtained. To analyze the preferred aerosol type for the dates with high content of suspended particles in the air, the CALIPSO satellite data were used. It is shown that the smoke recorded in the Sevastopol atmosphere on 19.02.2020 could lead to increase of the PM10 particles concentration. A day before the increased concentrations of suspended particles were revealed in the Sevastopol atmospheric air, the CALYPSO satellite data on aerosol typing over the Black Sea had shown predominance of the smoke aerosol in the atmosphere over the region under study. Conclusions. The results of the investigation shows that in the atmosphere of Sevastopol, the cases when the PM2.5 and PM10 particles contents exceeded the maximum permissible daily average concentration by up to 3.4 times were detected. It was found that the main cause of air pollution with micro-particles in Sevastopol was the transfer both of air masses from the deserts in the African continent and Asia and the burning biomass aerosol (smoke). Air pollution with the PM10 particles caused by the local source, namely soil exсavation in immediate proximity to the air sampling point, was less significant.

Issledovaniye vzveshennykh mikrochastits v atmosfere beregovoy zony Chernogo morya po naturnym i sputnikovym dannym

Purpose. One of the most pressing problems of large cities is air pollution resulting from presence of various large and fine particles in the air. These micro-particles can be transported by the air currents over considerable distances, as well as coagulate various substances also present in the atmosphere. The purpose of the work is to study the content of particulate matter of 2.5 and 10 microns (PM2.5 and PM10) in the atmosphere of Sevastopol, as well as the processes affecting their concentration. Methods and Results. During the period from February to June, 2020, the scientists of Marine Hydrophysical Institute (MHI), RAS measured mass concentration of PM2.5 and PM10 in Sevastopol using the “Atmas” dust analyzer. A total of 180 measurements of the micro-particle concentrations in the air of Sevastopol were done, and 60 values of the PM2.5 and PM10 daily average concentrations were obtained. To analyze the preferred aerosol type for the dates with high content of suspended particles in the air, the CALIPSO satellite data were used. It is shown that the smoke recorded in the Sevastopol atmosphere on 19.02.2020 could lead to increase of the PM10 particles concentration. A day before the increased concentrations of suspended particles were revealed in the Sevastopol atmospheric air, the CALYPSO satellite data on aerosol typing over the Black Sea had shown predominance of the smoke aerosol in the atmosphere over the region under study. Conclusions. The results of the investigation show that in the atmosphere of Sevastopol, the cases when the PM2.5 and PM10 particles contents exceeded the maximum permissible daily average concentration by up to 3.4 times were detected. It was found that the main cause of air pollution with micro-particles in Sevastopol was the transfer both of the air masses from the deserts in the African continent and Asia, and the burning biomass aerosol (smoke). Air pollution with the PM10 particles caused by the local source, namely soil exсavation in immediate proximity to the air sampling point, was less significant.

Changes in the Oxygen Regime in the Deep Part of the Black Sea in 1980–2019

Purpose. Assessing changes in the oxygen regime of the deep-water part of the Black Sea under the influence of climatic and anthropogenic factors over the past 40 years is the goal of the work. Methods and Results. For the analysis, the expedition data (2015–2019) and those from the Databank of the Marine Hydrophysical Institute, Russian Academy of Sciences, (1980–2013) were used. The data for the deep-water part of the Black Sea (the depths exceeding 200 m) were selected from the array. The data on hydrophysical and hydrochemical parameters were subjected to expert assessment, and those including random errors in the values were excluded from the array. Then the average profiles of temperature, salinity, oxygen concentration, oxygen saturation, and nitrates concentration were plotted in the density scale (σt). Averaging was carried out by the inverse distance method followed by additional smoothing by the low-frequency filtering method. Conclusions. Against the background of the tendency of temperature increase in the upper layers of the water column and decrease of winter convective mixing intensity, the oxygen supply diminishes in all the layers of the Black Sea aerobic zone. Having been analyzed, of the data for the 1980–2019 period showed that at the present stage, a "regime shift" resulting from the joint effect of climate changes and anthropogenic load took place in the ecosystem of the deep-water part of the Black Sea. Decrease in the oxygen saturation of water throughout the entire thickness of the aerobic zone shows that the process of the Black Sea basin eutrophication constitutes a significant factor affecting oxygen dynamics in the Black Sea waters.

Izmeneniye kislorodnogo rezhima glubokovodnoy chasti Chernogo morya za period 1980–2019 gody

Purpose. Assessing changes in the oxygen regime of the deep-water part of the Black Sea under the influence of climatic and anthropogenic factors over the past 40 years is the goal of the work. Methods and Results. For the analysis, the expedition data (2015–2019) and those from the Databank of the Marine Hydrophysical Institute, Russian Academy of Sciences, (1980–2013) were used. The data for the deep-water part of the Black Sea (the depths exceeding 200 m) were selected from the array. The data on hydrophysical and hydrochemical parameters were subjected to expert assessment, and those including random errors in the values were excluded from the array. Then the average profiles of temperature, salinity, oxygen concentration, oxygen saturation, and nitrates concentration were plotted in the density scale (σt). Averaging was carried out by the inverse distance method followed by additional smoothing by the low-frequency filtering method. Conclusions. Against the background of the tendency of temperature increase in the upper layers of the water column and decrease of winter convective mixing intensity, the oxygen supply diminishes in all the layers of the Black Sea aerobic zone. Having been analyzed, the data for the 1980–2019 period showed that at the present stage, a “regime shift” resulting from the joint effect of climate changes and anthropogenic load took place in the ecosystem of the deep-water part of the Black Sea. Decrease in the oxygen saturation of water throughout the entire thickness of the aerobic zone shows that the process of the Black Sea basin eutrophication constitutes a significant factor affecting oxygen dynamics in the Black Sea waters.

Seawater Salinity Estimating Module Based on the Sound Velocity Measurements

Purpose. Reliability of knowledge about the ocean dynamics and climate variability is largely limited for lack of systematic in situ observations of the sea surface layer salinity, which is one of the basic hydrological parameters determining circulation and stratification of the water masses. The study is aimed at developing an autonomous device for long-term monitoring of salinity in the seawater upper layer. Methods and Results. One of the most effective tools for in situ observations of the ocean upper layer is the global network of surface drifting buoys – drifters. At present, the network consists of more than 1500 buoys, but only a few of them provide sea surface salinity observations within the framework of a limited number of pilot experiments. In the drifters, salinity is calculated by the traditional method using the results of the electrical conductivity and temperature measurements. There are a few problems related both to the principle of determining salinity by this method and to providing long-term stable running of conductivity sensors under the conditions of pollution and biological fouling. A drifter equipped with the module for the sound velocity and temperature measurements used for calculating salinity by an alternative method just aboard the drifter, was developed in Marine Hydrophysical Institute, Russian Academy of Sciences. The sound velocity and temperature module includes a specially designed time-of-flight sound velocity sensor with the fixed base and a quartz temperature sensor. In course of two years, numerous laboratory and in situ tests of several prototypes of the sound velocity and temperature module were performed. The laboratory tests showed that the repeatability limits for the results of the sound velocity measurements in the distilled water were 0.02 m/s. According to the data of the long-term in situ tests performed at intensive biological fouling, the error of salinity estimation resulted from of the sound velocity and temperature measurements were within 0.05 ‰. This result permits to expect that the sound velocity and temperature module parameters will remain stable in real conditions of long-term autonomous operation. Conclusions. The obtained results make it possible to recommend application of the drifters equipped with the modules for the sound velocity and temperature measurements as an effective tool for regular operational monitoring of the salinity field of the upper sea layer.

Matematicheskoye modelirovaniye dinamiki granulometricheskogo sostava donnykh otlozheniy Balaklavskoy bukhty pod vozdeystviyem shtormovogo volneniya

Purpose. Based on the mathematical modeling methods, influence of the wind waves on redistribution of the sand fractions in the semi-closed estuary-type water area is estimated using the Balaklava Bay as an example. Methods and Results. A two-dimensional version of the XBeach model with a constant grid spacing 10 m was used. The characteristics of wind waves were preset using the JONSWAP spectrum implying fixed height, wave period and various combinations of the wave direction. The calculations were carried out for a storm event lasting about 12 hours once a year. The in-situ data on the particle size distribution in the bottom sediments resulted from the monitoring observations performed by the Marine Hydrophysical Institute, Russian Academy of Sciences, in the Balaklava Bay region was used in the numerical experiments. Conclusions. The results of modeling showed that the basic determining factors regulating the sediments movement were the depth and the bottom slope. It is noted that changing of the bottom inclination angle between the isobaths 6–7 and 7–8 m leads to deposition of the large and medium fractions, and in the area between the isobaths 9–10 and 10–12 m – to accumulation of fine sand. It was revealed that in the Balaklava Bay water area, the main redistribution of sand material caused by the storm waves took place within the southern basin, as well as at the bay exit in the coastal zone of the Megalo-Yalo Bay. This is primarily determined by the features of the Balaklava Bay coast orography, namely, the knee-shaped narrowness separating the northern and southern basins. Nevertheless, in the isolated northern part of the Balaklava Bay being affected by the storm waves, insignificant dynamics of sand material was observed. The fractions of bottom sediments are redistributed from the western coast to the central part of the basin and to the eastern coast of the bay.

Modul' otsenivaniya solenosti morskoy vody na osnove izmereniy skorosti zvuka

Purpose. Reliability of knowledge about the ocean dynamics and climate variability is largely limited for lack of systematic in situ observations of the sea surface layer salinity, which is one of the basic hydrological parameters determining circulation and stratification of the water masses. The study is aimed at developing an autonomous device for long-term monitoring of salinity in the seawater upper layer. Methods and Results. One of the most effective tools for in situ observations of the ocean upper layer is the global network of surface drifting buoys – drifters. At present, the network consists of more than 1500 buoys, but only a few of them provide sea surface salinity observations within the framework of a limited number of pilot experiments. In the drifters, salinity is calculated by the traditional method using the results of the electrical conductivity and temperature measurements. There are a few problems related both to the principle of determining salinity by this method and to providing longterm stable running of conductivity sensors under the conditions of pollution and biological fouling. A drifter equipped with the module for the sound velocity and temperature measurements used for calculating salinity by an alternative method just aboard the drifter, was developed in Marine Hydrophysical Institute, Russian Academy of Sciences. The sound velocity and temperature module includes a specially designed time-of-flight sound velocity sensor with the fixed base and a quartz temperature sensor. In course of two years, numerous laboratory and in situ tests of several prototypes of the sound velocity and temperature module were performed. The laboratory tests showed that the repeatability limits for the results of the sound velocity measurements in the distilled water were ± 0.02 m/s. According to the data of the long-term in situ tests performed at intensive biological fouling, the error of salinity estimation resulted from of the sound velocity and temperature measurements were within ± 0.05 ‰. This result permits to expect that the sound velocity and temperature module parameters will remain stable in real conditions of long-term autonomous operation. Conclusions. The obtained results make it possible to recommend application of the drifters equipped with the modules for the sound velocity and temperature measurements as an effective tool for regular operational monitoring of the salinity field of the upper sea layer

РАСТВОРЕННОЕ ОРГАНИЧЕСКОЕ ВЕЩЕСТВО В ВОДАХ БУХТЫ АБРАМОВА (КРЫМ) ЛЕТОМ 2019 Г

Based on data of the monitoring carried out by Marine Hydrophysical Institute in summer of 2019, the structure and the pattern of temporal variations in the field of concentration of dissolved organic matter (DOM) in the Abramov Bay (Crimea) are revealed. The response of the DOM concentration field to the atmospheric synoptic processes is monitored. The variation patterns of the analyzed field structure under conditions of intensive desalination of the coastal zone by storm water, as well as under influence of upwelling and typical wind conditions for summer are determined. Statistical data on the DOM concentration variability in the Abramov Bay apex are presented.

Особенности литодинамики галечных пляжей южного берега Крыма

The results of the study of the peculiarities of lithodynamics of pebble beaches of the South Coast of Crimea based on the long-term monitoring of the state of beaches performed at the Black Sea Hydrophysical Subsatellite Proving Ground of the Marine Hydrophysical Institute of the Russian Academy of Sciences in the settlement of Katsiveli are presented. Long-term changes of the beach of Limensky Bay since 1950 and of beaches of the shore protection structures since 1988 are characterized. The volume of income and outcome of pebbles during the change of wind-wave regimes was estimated by the example of Limensky Bay beach and the artificial beaches of the coast protection structures in the coastline section from Katsiveli to Ponizovka settlement. The most influential factor in the formation of the pebble beaches of the Southern Coast of Crimea is the change in alongshore wind-wave regimes in the “days-months” time scale, which leads to significant fluctuations in sea level near the coast and a corresponding change in the directions of the bottom current velocity components perpendicular to the shoreline. The largest expense and income of beach-forming material (up to 1 m3/day per linear meter of beach) occurs during storms, respectively, with wind-wave regimes of the eastern and western directions. The largest irreversible removal of the mass of beach-forming materials during the change in wind-wave regimes occurs from the eastern and central sections of the bays and artificial beaches of coastal protection structures, and partial restoration of beaches—on their western sections. Natural underwater reefs in the coastal waters of bays and artificial beaches of shore protection structures contribute to the preservation of beaches in them. The reason for the gradual average long-term degradation of beaches may be the predominance of eastern storm winds over western ones in conditions of blocking the natural income of beach-forming materials from the coast by the coastal infrastructure objects.

Исследование временной изменчивости параметров вертикальной структуры вод в прибрежной зоне южного Крыма

The issues of the formation and temporal variability of the vertical structure of the Black Sea waters off the coast of the southern Crimea are considered. A large array of instrumental measurement data obtained in the second half of 2013 (June–December) during operational monitoring of the vertical temperature profile in the area of Stationary oceanographic platform of the Marine Hydrophysical Institute in the coastal zone near Cape Kikineiz is used. The measurements were carried out using a thermoline, which is a system of temperature sensors distributed in depth from the surface to the bottom. To study the vertical structure of the temperature field, a model of two-layer stratification is considered, when two quasi-homogeneous layers (the upper one is warmer and the lower one cold) are separated by a layer of large vertical temperature gradients—the thermocline. A number of parameters of the vertical structure of waters were calculated: the vertical temperature gradient, its maximum values and depth of occurrence, the temperature of the thermocline core (if it was recorded) and quasi-uniform layers, the temperature difference between these layers, and the thermocline thickness. The median estimates of the daily values of the listed parameters are analyzed. Specific cases of transformation of the vertical profile of water temperature during the upwelling and downwelling processes are considered. It is shown that the temporal variability of the parameters of the vertical structure is significant, especially in the summer hydrological season. The main contribution to the variability is caused by the seasonal course of the heat flow from the atmosphere through the sea surface and surge processes (upwelling and downwelling) in the summer period caused by abrupt changes in the alongshore wind component. In the autumn hydrological season, the thermocline is recorded sporadically with a slight gradient in the form of the lower boundary of the subsurface layer of daytime heating, or a thin bottom layer.

Современные исследования динамики вод в северо-западной части Черного моря по данным LADCP

In this work a result of preliminary analysis of current measurements collected in fourteen large-scale expeditions of the Marine Hydrophysical Institute in 2016–2019 in the north-eastern part of the Black Sea is presented. It is shown that the use of the Lowered Acoustic Doppler Current Profiler (LADCP) significantly increases the information content of the expedition materials, opening up new opportunities in the experimental study of water dynamics. Based on the materials of the expeditions, it was found that the upper layer of shear baroclinic currents in the measurement area is limited by the isopycnic depth with a potential density of ~16.75 kg/m3 (~350 m). At this depth, the variability of the buoyancy frequency with the depth changes from a power-law to an exponential dependence. The same depth limits the penetration of seasonal variations of the average kinetic energy into the water column. The highest values of the average kinetic energy are observed in April-May and November–December, the lowest—in June–August. The ratio of the maximum energy values (summer) to its minimum values (spring, late autumn, winter) was ~3. The Rim Black Sea Current is most pronounced near the Crimean Peninsula in the spring and winter seasons. In summer and autumn, the horizontal distribution of the current velocity in depths of 30–80 m is less structured, which is caused by the seasonal intensification of mesoscale processes. At a number of stations, the current velocity profiles contain fragments with a well-defined harmonic variability of the current velocity components with depth, which can be interpreted as the manifestation of near-inertial internal waves. In most cases, the rotation of the current velocity vector with depth occurs clockwise, which determines the main direction of propagation of the inertial internal waves into the water column. The example of one of the stations shows the significant contribution of such waves to the value of shear. This fact suggests a significant influence of near-inertial internal waves on the processes of vertical turbulent exchange in the water column.

Основные объекты антропогенного воздействия на водную среду Керченского пролива по данным многолетних гидрооптических и гидрохимических исследований

Based on expeditionary data of Marine Hydrophysical Institute (MHI, Sevastopol) and Southern Research Institute of Marine Fisheries and Oceanography (YugNIRO, Kerch), the main objects of economic activity that have anthropogenic impact on the Kerch Strait waters and adjacent areas of the Sea of Azov and the Black Sea are identified. These are ports, cargo terminals, dump zones, raid transshipment points, etc. Results obtained by optical methods were compared with those of long-term standard hydrochemical complex observations of water pollution in the studied region.