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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.

Introduction. In the present paper structural regularities of the total suspended matter (TSM) and dissolved organic matter (DOM) content fields and the dissolved oil products (OP) concentration in the dredging and dumping areas in the Kerch Strait and the adjacent regions are identified based on the oceanographic data of the expeditions of the Marine Hydrophysical Institute and the Southern Research Institute of Marine Fishery and Oceanography. Data and methods. The data of nine complex expeditions in the Kerch Strait in 1999–2013 were analyzed. The concentrations of all the substances under study were determined applying the optical methods. All the surveys were carried out in a probing mode using the Kondor optical probe. Results. It is shown that sea dredging in the commercial port of Kerch was accompanied by significant increase of the total suspended matter content; its concentration was dozen times higher than that in the adjacent area. High content of the total suspended matter, characteristic for the port and the surrounding waters, contributes to accumulation and deposition of the anthropogenic dissolved organic matter, which concentration significantly exceeds the natural one. It is revealed that the dumping zones remain the sources of seawater environment pollution. The pronounced local maxima of the total suspended matter, dissolved organic matter and dissolved oil products concentrations were revealed in the bottom layer just in these zones: here they 1.5–3 times exceeded the natural standards of the considered characteristics. Discussion and Conclusions. Dredging is the most significant factor determining the high concentration of suspended matter of anthropogenic origin in the Kerch Strait. The soil removed during dredging has an extremely low compaction and abnormally high fluidity that promotes intensive erosion of the dumping zones and further spread of suspension in the ambient waters. Dredging and dumping zones are not only pockets of environmental hazards; they are also unfavorable for navigation.

Based on the actual and climatic oceanological data, the notions on composition of the field of the dissolved organic matter content in the Taganrog Bay, from the Don River mouth to the Azov Sea adjacent water areas are obtained. The features of the natural marginal filter of the Don mouth and the runoff waters in the bay are considered. Significant heterogeneity in the field of the considered characteristic (its concentration exceeds the natural standard in the Don mouth) is revealed, that can probably be a consequence of the dissolved organic matter anthropogenic sources, in other words, waste waters from the settlements. The pronounced frontal section, i. e. a natural marginal filter, was revealed in the field of the dissolved organic matter concentration. It was located along the maritime part of the Don River mouth within the narrow shore strip (its width is approximately 0.5–1.0 miles). Across this natural marginal filter, the dissolved organic matter concentration reduced abruptly towards the open sea. Up to 50% of the dissolved organic matter brought to the marine part of the Don mouth remained on the filter. It is revealed that salinity and the dissolved organic matter content in the marginal filter area are closely bound by the backward correlation dependence with the coefficient -0.87. It is shown that the dissolved organic matter concentration in the Taganrog Bay decreases in the area between the marginal filter and the runoff front from 20 to 3 mg/l, and complete transformation of the bay waters saturated with the dissolved organic matter is observed in the runoff front which, in course of the major part of a year, is located at the bay outlet. Seaward off the front external boundary (isohaline 10 PSU), the fields of salinity and dissolved organic matter content are characterized by spatial homogeneity with the 10-13 PSU salinity and the dissolved organic matter concentration 1-3 mg/l which are typical of the Azov Sea open water areas. It is found that weakly pronounced vertical stratification of the field of the dissolved organic matter concentration is peculiar to all the studied water areas.

Local and large-scale upwellings in the Kerch Strait and in the Black Sea adjacent waters are considered based on the contact and satellite data. The spatial scales and the temporal variability characteristics of these phenomena as well as regularities of thermohaline field transformation are identified. It is shown that a stable northwestern wind generates local upwelling pockets in the southern and central areas of the Kerch Strait. Quite a rare natural phenomenon when a wind-generated local upwelling induces temperature rise in the coastal waters is described. The upwelling observed in late September is accompanied by water temperature growth in the strait. It is revealed that the Black Sea subsurface waters that flow to the strait within the upwelling circulation system and that are of total suspended and dissolved organic matters low concentrations, contribute to improving water quality. Large-scale upwelling is originated in the Feodosiya Gulf; its influence extends to the Kerch Strait and to a wide strip along the eastern coast of the Crimea. The cycle of this kind of upwelling varies within the range of 1-8 days. Maximum frequency is typical for an upwelling cycle of about 24 hours. Considerably variable on interannual scale temporal characteristics of a large-scale upwelling off the eastern coast of the Crimea and in the Kerch Strait are shown on the quantitative level.

On the basis of the analysis of the archival data, we reveal some regularities of the interannual and seasonal variations of the parameters of atmospheric transport, winds, air temperature, the amount of atmospheric precipitation in the Kerch region, the temperature of water in the Kerch Strait, and the water discharge through the strait observed for about the last two decades. It is shown that the intensities of the southeast atmospheric transport and wind activity predominant for the previous 30-yr period decreased for the analyzed time period as compared with the previous period, whereas the amount of atmospheric precipitation and the annual average temperatures of water in the strait and air in the Kerch region increased. We also reveal the presence of direct qualitative relationship between the intensity of atmospheric transport over the Kerch Strait and the water discharge in its water area.

Peculiarities of the ice situation in the Sea of Azov and the Kerch Strait during the cold winter of 2005/06 are considered using a set of satellite images in the visible range, accumulated at the Southern Research Institute of Marine Fisheries and Oceanography (in Kerch). The ice conditions of the water area over the last years are examined and compared to the climatic data.

We study the seasonal and interannual variations of the field of sea-surface temperature (SST) in the Southwest Atlantic on the basis of the analysis of three data arrays, namely, the Levitus-Boyer-1994 hydrological array, the WOD-98 actual database, and the data of satellite measurements of SST. We perform the comparative analysis of the amplitude-phase characteristics of the annual course of the SST field and discuss the distinctive features of its seasonal and interannual variations. It is shown that the results obtained by using different data arrays are in good agreement. The values of the coefficient of linear correlation are equal to 0.7–0.9. It is discovered that the maximum seasonal variations of SST are observed in the zone of confluence of the Falkland and Brasil Currents in the vicinities of the South Subtropical and Antarctic Polar fronts. The minimum seasonal variations are recorded in the Antarctic region and in the Weddell Sea. The satellite data demonstrate that the level of interannual variability is high in the zones of climatic fronts.

On the basis of the many-year monthly average thermohaline data of the oceanographic array, we study some regularities of the seasonal cycle in the fields of temperature, salinity, and the characteristics of water masses in the Drake Passage. We obtain and analyze the amplitude and phase parameters of seasonal oscillations of the investigated quantities. By using the volumetric statistical T, S-analysis, we deduce quantitative estimates of the annual variations of the volumes of main water masses in the Drake Passage. Possible mechanisms responsible for the phenomena observed in this region are discussed.

The vertical profiles of temperature and salinity are classified by using the contemporary array of actual and monthly average archive oceanographic data. A scheme of decomposition of the investigated water area into zones according to the typical features of vertical stratification of the thermohaline field is proposed. The criterion of maximum of the horizontal temperature and salinity gradients is used to select and map the principal large-scale frontal boundaries. The parameters of fronts and some regularities of their seasonal variability are described and the data on water masses interacting in the analyzed system of fronts are presented.

На основі обробки та аналізу даних експериментальних океанографічних досліджень, проведених у лютому-березні 2002 року на акваторії міжострівної зони архіпелагу Аргентинські о-ви в ході 7-ої української антарктичної експедиції, виявлені особливості вертикальної стратифікації гідрологічних і гідрохімічних елементів. Подані і проаналізовані відомості про течії. Результати порівнювались з даними попередніх океанографічних досліджень регіону, проведених у рамках перших трьох національних морських експедицій в Антарктику. Показано, що велика кількість плавучого льоду в літній сезон у районі станції супроводжується аномальними гідрологічними умовами і слабкою динамікою вод.

We present the results of biological and oceanographic investigations performed in the Weddell and Scotia Seas within the framework of the first (January–June, 1997) and second (January–June, 1998) Ukrainian Antarctic marine expeditions. We reveal some regularities in the space distribution of the aggregations of krill and salpae depending on the abiotic (hydrophysical) environmental factors and discuss possible mechanisms promoting the formation of aggregations of krill and salpae in the Antarctic waters.

Based on an analysis of the monthly average diagrams of dynamic topography, we reveal some specific features of the geostrophic circulation of waters in the South Atlantic Ocean. We present an improved picture of the structure and annual variability of the climatic large-scale circulations. They are compared with similar climatic cells of the large-scale circulation of waters in the north part of the ocean. Quantitative estimates of the characteristics of seasonal oscillations of the field of dynamic heights are obtained.

On the basis of the data of a comprehensive oceanographic experiment carried out in the course of the fifth national expedition to Antarctica in March–April 2000, we study the structure and kinematics of waters in the region of the Argentine Islands, where the “Akademik Vernadskii” Ukrainian Antarctic Station is located. We study the regularities of the thermohaline stratification of waters, the characteristics of the field of dissolved oxygen, and the distribution of the light attenuation coefficient. The data on tidal and residual currents are also presented.

On the basis of the results of calculation and analysis of the characteristics of space variability of the geostrophic component of large-scale zonal currents in the tropical zone of the South Atlantic, its intrayear oscillations, and the components of tangential wind stresses, we establish the regularities of seasonal variability of the system of gradient currents on the ocean surface depending on wind conditions. We describe the specific features of seasonal meridional fluctuations of the midstreams of the geostrophic component of zonal large-scale currents and the intrayear variations of their velocity.

On the basis of the data of the complex oceanographic experiment carried out in the course of the second Ukrainian Antarctic expedition in March 1998, we study the structure and kinematics of waters in the region of the archipelago of Argentine Islands. The regularities of thermohaline stratification of waters are discovered. We determine the most important environmental parameters premoting the variability of hydrophysical fields on time scales varying from several days up to a week, analyse the data of actual observations over the currents, and estimate the relative contribtions of diurnal and semidiurnal tidal waves to the total dispersion of hydrophysical parameters of the environment. The residual currents are filtered out. We propose a hypothesis about the mechanism of their formation. Various types of tidal currents are revealed and the directions of propagation of diurnal and semidiurnal tidal waves are determined.

The peculiarities of seasonal variability of the calculated sound speed and elements of its vertical stratification in the northern Black Sea continental slope are considered. Typical acoustic structures have been identified. The impact of seasonal variability of the sound speed upon the ray characteristics of acoustic fields is studied.

The paper concentrates on the structure and synoptic variability of the meteorological, hydrophysical and chemical fields in the Somali continental shelf area during summer monsoon. Tidal front is shown to be a typical element of the water stratification in the studied area, whose state and dynamics thoroughly in.quence the fisheries situations. It has been found out that commercial aggregations of fishes regularly pooled up and dispersed in the frontal zone, depending on the natural synoptic-scale processes taking place.

The CTD survey data collected in the course of implementation of the POLYGON-70 and POLYMODE projects are applied to gain a deeper insight into the structure of the sound speed field and elements of its vertical stratification in the areas of synoptic-scale vortical formations of the North-West Atlantic. The effect of vortical features on the structure of the acoustic fields is studied in the ray approximation.

Usingin situ temperature and salinity observations from the Marine Hydrophysical Institute's oceanographic data set, regularities of the formation of structure and seasonal variability of the calculated sound speed field, as well as elements of the latter's vertical stratification in the South Crimea shelf area, have been studied. The ray approximation is applied to consider the influence of seasonal variations of the vertical hydrologic-and-acoustic structure on the propagation of sound in the sea.

Using archived historical data on the temperature/salinity distribution, this paper describes the structure of the mean seasonal and the actual field of the computed speed of sound in the Gulf Stream region. The formation of acoustic channels of large, medium, and small size is considered, depending on the vertical thermohaline structure of waters. The paper provides statistical characteristics of the sound speed field and acoustic channels of waters interacting in the Gulf Stream system.

This paper examines the oceanographic situation in the north-eastern Arabian Sea shelf area during the period when the trade winds change. The location and intensity of the discharge front there have been found to be dictated by tidal events and the wind regime. It is shown that commercial fish shoals move over the water column along with the front and that fish catches are largest when the front is steady.

A classification based on the number and types of large-scale acoustic waveguides is proposed for the mean seasonal profiles of sound speed propagation. A scheme for North Atlantic zoning, using typical curves of the sound speed vertical distribution, is given. The channel axis's position is shown not to depend on the water mass haline properties, being controlled by the temperature field vertical stratification.

Regularities in the structure and variability of the acoustic characteristics of Guinean shelf waters during the rainy season have been identified as a result of the generalization of the sound speed fields derived from temperature and salinity observations. Three areas with qualitatively different hydroacoustic properties have been revealed, namely, (i) near-shore shallow waters, where a near-surface haline acoustic channel occurs by virtue of intensive seawater freshening; (ii) a discharge front accommodating an intermediate acoustic waveguide in the temperature jump layer; and (iii) off-shore shelf areas displaying a characteristic alteration of the sound speed vertical gradient sign at thec(z) profile.

Synoptic variability of the sound speed and parameters of the SOFAR channel in the tropical Atlantic are considered. The synoptic component of the temporal and spatial dispersions of sound speed is singled out. The synoptic processes are shown to essentially affect the vertical hydroacoustic structure on a 1-month scale. It has been found that synoptic variations in the sound speed field penetrate as far as the SOFAR channel axis and deform it considerably.

The vertical structure of the climatic and seasonal fields of the estimated speed of sound in the north-east Atlantic Ocean is considered. Zonation according to typicalc(z) profiles allowing for seasonal variations was carried out. It is shown that the water areas with a dual-channel vertical hydroacoustic structure vary essentially throughout the year. The features of the structure of the sound speed field in the lenses of the Mediterranean Sea waters are investigated. The effect produced by a lens on the characteristics of the sound propagation is studied.

Large-scale CTD survey data are used to calculate the acoustic velocity in the North Tropical Atlantic. It has been stated that a characteristic feature of the vertical hydroacoustic structure in this region is associated with the presence of numerous local sound channels in the subsurface and intermediate layers. Characteristics of these channels are given and possible causes of their origin are discussed. It is shown how local acoustic waveguides affect the sound beam trajectory.

The variability of the sound speed vertical distribution in high-salinity and freshened tropical waters has been computed using the intense convection model. It is shown that the most complicated transformation of theC(z) profile is induced by haline convection in freshened oceanic waters. Computation results are collated with observed data.

The peculiarities of the vertical hydroacoustic structure of surface water masses in the tropical Atlantic are reported. The near-surface acoustic channel in areas of strong freshening of oceanic waters by continental discharge and rainfall is studied. Quantitative characteristics of the seasonal variability of the channel's parameters are given. The mechanism responsible for the long-range acoustic conductivity in the upper layer of waters is analysed. The areas of maximum horizontal refraction in the near-surface layer are identified and the refraction angles of acoustic rays determined.

The geostrophic circulation of active and intermediate layers in the north Tropical Atlantic is analysed on the basis of data collected in the transatlantic study area in 1986–1987. Its seasonal features are also found. Quasi-steady eddy formations and their relation to the bottom topography are considered for the intermediate region. The influence of these formations on the kinematics of large-scale currents in this layer is substantiated. Structures of large-scale tropical cyclonic and anticyclonic eddy formations are specified. A strategy for further studies in the Tropical Atlantic is suggested.