Purpose. The aim of the study is to analyze the features of mean long-term structure and intra-annual variability of the characteristics of temperature fronts on the ocean surface in the Patagonian shelf region. Methods and Results. Mean daily values of the ocean surface temperature from the NOAA OI SST data and the geostrophic velocity components on the surface at the nodes of a 0.25 degrees regular grid from the CMEMS reanalysis for 1993-2020 were used. . It is shown that at the western periphery of a largescale cyclonic meander formed by the currents in the Patagonian shelf region (south of 45 degrees S), three branches of the Subantarctic Front are traced; they correspond to the West Falkland Current and to two jets of the East Falkland Current. North of 45 degrees S, where one Falkland Current jet is observed, one branch of the Subantarctic Front is identified. On the eastern periphery of the meander, the front corresponding to the common stream of the Brazil Current and the Falkland Return Current is revealed. Besides, south of 40 degrees S, a separate branch of the Subantarctic Front corresponding to one more recirculation of the Falkland Current is observed. It is shown that at the meander western periphery, the branches of the Subantarctic Front are most intensified in February - March, at its eastern periphery - in March - April, and at the meander northern peak (in the zone of the Brazil - Falkland Confluence) - in April - May and November. Conclusions. . It is found that on the western periphery of the cyclonic meander, south of 45 degrees S, the main branch of the Subantarctic Front approximately follows the 900-1000 m isobaths, north of 45 degrees S - the 150-170 m isobaths, and closer to the Brazil - Falkland Confluence - the 50-60 m isobaths. At the meander eastern periphery, north of 40 degrees S, the main branch of the front is very close to the 800- 1000 m isobaths, south of 40 degrees S - to the 1000-2500 m isobaths. It has been established that the differences between the seasonal cycles of intensity of the Subantarctic Front branches are related to the dissimilar warming and cooling rates of surface waters separated by these branches.

Purpose. The aim of the study is to specify the features in changes of the Black Sea surface water temperature off the Crimea coast on a synoptic scale in summer 2022 based on the contact and satellite measurements of water temperature and surface wind. Methods and Results. The data of hydrological measurements carried out during the 122nd (June 7-23, 2022) and 123rd (August 16-31, 2022) cruises of the R/V Professor Vodyanitsky in the northern part of the Black Sea were used. Sea water temperature was measured by the CTD complex IDRONAUT OCEAN SEVEN 320 PlusM, and the wind speed and direction - by the AIRMAR-220WX ship meteorological station. The study also included the daily averaged satellite-derived data on sea surface temperature taken from the Black Sea - High Resolution L4 Sea Surface Temperature Reprocessed with the 0.01 degrees x 0.01 degrees spatial resolution, as well as the data on wind speed taken from the Global Ocean Hourly Sea Surface Wind and Stress from Scatterometer and Model with the 0.125 degrees x 0.125 degrees spatial resolution (Copernicus Marine Environment Monitoring Service). Based on the contact and satellite measurements, statistical characteristics of the water temperature and wind speed distributions were calculated. It was shown that the differences in temperature distributions revealed from the data of the two-stage surveys in the above-mentioned cruises had been conditioned by the features of a temperature seasonal cycle and by the synoptic variations of surface wind. A significant inverse correlation was found between the wind speed module and the temperature, the maximum level of which was observed in the western part of the survey area, approximately between Cape Aiya and Cape Sarych. Conclusions . It is shown that based on the contact and satellite measurement, in summer 2022, the values of synoptic temperature anomalies on the sea surface were the highest in the area of noticeable coastal shelf expansion, i.e., in the Feodosiya Bay and between Sarych and Ayu-Dag capes. The temperature were conditioned the variations in the local wind speed.

Purpose. The aim of the work is to clarify the spatial structure of the climatic dynamic fronts (geostrophic current jets) and to estimate the relationship between their position and that of the large-scale temperature fronts on the surface of the Scotia Sea and the adjacent water areas in the southwestern part of the Atlantic sector of Antarctica. Methods and Results. The daily averaged data arrays of the CMEMS (1993-2017) and NOAA OI SST (1982-2017) reanalysis at the regular 0.25 degrees grid were used. The CMEMS reanalysis contains the sea surface geostrophic velocity values, the NOAA OI SST reanalysis - the sea surface temperature ones which were reduced to the climatic form through their averaging for each month of the corresponding periods. Position of the current jets and the temperature fronts was determined using the maximums of the geostrophic velocity components and the extremes of the temperature horizontal gradients. The updated scheme of the average long-term position of dynamic fronts was constructed. It shows that in the areas of the most pronounced bottom topography inhomogeneities (the northern boundary of the Falkland Plateau and the Tierra del Fuego shelf, the boundaries of the Falkland Islands shelf and the Birdwood Bank, the Shackleton Ridge and the South Shetland Islands shelf), the fronts do not change their latitudinal position during a year. It is revealed that in most of the water area, the temperature horizontal gradient extremes (temperature fronts) correspond to the geostrophic velocity maximums (dynamic fronts). The Northern and Central Branches of the Antarctic Circumpolar Current are most clearly manifested in the temperature field. In general, in the water area under study, the average annual latitudinal position of the Subantarctic and Antarctic Polar Fronts is displaced to the south relative to the position of the Northern and Central branches jets of the Antarctic Circumpolar Current by 0.250.5 degrees and 0.25-1 degrees, respectively. Conclusions. It is shown that, being influenced by the bottom topography, the large-scale jets of geostrophic currents form intense topographic meanders and recirculation branches which are stably manifested on the climatic scale. The Antarctic Circumpolar Current branches being affected by the bottom topography, can merge forming the joint flows, and then diverge forming a system of separate jets again. It is found that the main spatial features of frontal structure in the geostrophic velocities field persist throughout the whole year and are conditioned mainly by the bottom topography. The most of the dynamic fronts are shown to be clearly pronounced in the temperature field on the surface during a year. A high level of linear correlation between the positions of temperature fronts and current jets was revealed; the correlation coefficient values are 0.6-0.97.

Представлены результаты гидролого-гидрооптических измерений, выполненных весной (22.04–17.05) и летом (29.07–10.08) 2021 г. в северо-восточной части Черного моря в ходе 116-го и 117-го рейсов НИС «Профессор Водяницкий». Показано, что весной, когда основная струя Основного черноморского течения располагалась относительно далеко от берега, и происходил интенсивный сток рек, область с высоким содержанием общего взвешенного вещества представляла широкую полосу, вытянутую вдоль побережья Краснодарского края. Летом, когда речной сток был ослаблен, а Основное черноморское течение проходило ближе к берегу, максимальные значения концентрации общего взвешенного вещества отмечались в относительно узкой полосе примерно между Сочи и Туапсе. Сезонная изменчивость вертикальной структуры концентрации общего взвешенного вещества проявилась в том, что весной максимум мутности отмечался на поверхности, а летом он опускался в слой сезонных термоклина и пикноклина.

Here we describe the features of the horizontal and vertical distribution of total suspended matter in the northern part of the Black Sea and their relationships with the water temperature, salinity, and density fields measured at the identical grid during hydro-optical surveys from 2016 to 2020. The results show that the primary sources of increased total suspended matter concen trations in the northern part of the Black Sea are low-salinity and turbid waters of the Kerch Strait; runoffs of the Rioni, Enguri, and other rivers in the east of the survey area; together with freshened waters of the Dnieper, Dniester, and Danube runoff from the northwestern shelf. Higher turbidity was observed in the deep-water part of the sea, associated with the cyclonic gyres and meanders of the Rim Current effects. The total suspended matter vertical structure features an upper mixed layer, which usually coincides in thickness with the upper thermohaline upper mixed layer. Significant negative correlations were found for this layer comparing total suspended matter concentration versus temperature and salinity, while the correlation appears positive with density values. Below, a total suspended matter subsurface maximum was observed in the seasonal thermocline and pycnocline layer. The high turbidity layer appeared almost an order of magnitude thinner in the regions of maximum temperature gradients versus the areas where the temperature gradient was weak. A local total suspended matter minimum occurred below the cold intermediate core, corresponding to the main thermocline, halocline, and pycnocline layer. Beneath this minimum, there was a local increase of total suspended matter coinciding with the upper boundary of the hydrogen sulfide zone.

The structure and seasonal variability of temperature frontal zones and fronts in the Black Sea are studied on the basis of a modern high-resolution satellite data set. The distributions of the total temperature gradient allow us to distinguish the following frontal zones: the western frontal zone; the Turkish coastal frontal zone; the Anatolian upwelling frontal zone; the southeastern coastal frontal zone; northeastern, Crimea, and Kerch-Feodosia frontal zones; and the frontal zone of the deep part of the Black Sea. Large-scale fronts are identified within most frontal zones based on an analysis of distributions of meridional and zonal temperature gradients. It is shown that the combined effect of large-scale processes (seasonal warming and cooling of waters and their advection by the Rim Current) and regional factors (river discharge, coastline configuration, shelf width, development of upwelling, and formation of coastal eddies) produces significant spatiotemporal variability of the temperature field and, hence, frontal zones and fronts. It is ascertained that most fronts exist for several months. In the northern part of the sea, the fronts intensify mainly in winter due to an increase in the contrasts between warm Rim Current waters and colder coastal waters. The frontal zones near the southern coast of the sea intensify mainly in late spring–summer during the spring flood, the development of Anatolian upwelling, and active warming of waters in the eastern part of the sea.

Purpose. The aim of the work is to clarify the regional features of synoptic variability of the Black Sea surface temperature, to reveal its intra- and inter-annual changes and to assess the features’ relations with the large-scale atmospheric processes. Methods and Results. The satellite-derived data on the sea surface temperature in 1982–2018 from the Copernicus array were used; their temporal resolution was daily average and the spatial one – 0.04 degrees. These data showed that the maximum of temperature synoptic variability was observed in the coastal part of the northwestern shelf from the Dnieper-Bug estuary to the Danube delta, in the Karkinit Bay and in the Kerch Strait. In the deep sea, strong synoptic variability can be observed in the regions of the Eastern cyclonic gyre and the Batumi anticyclone. The greatest contribution of synoptic variability to the total temperature dispersion was observed in the Kerch Strait and to the south of the Kerch Peninsula. The level of multi-year average synoptic variability is lower or comparable with the level of the interannual variability in most of the water area, except for the Kerch Strait, the northwestern and the Bosporus shelves. It is revealed that in the climatic annual cycle the main maximum of synoptic variability is observed in May, a month before the maximum rate of surface water heating is achieved, the second maximum – in October, a month before the maximum rate of water cooling. The minimums are observed in February–March, during the period of maximum cooling of surface waters, and in August, during their maximum heating. Noticeable interannual changes of the level of temperature synoptic variability varying from −0.3 °С to 0.3 °С, were revealed. Conclusions. Synoptic variability of the Black Sea surface temperature is characterized by noticeable intra-annual and interannual variations. Its climatic annual cycle is of a semi-annual periodicity due to the processes of water cooling and heating. The maximum increase of the synoptic variability level on the interannual scale is observed after 2003 on the northwestern shelf. Significant correlation with the indices of the North Atlantic, East Atlantic and the East Atlantic–West Russia oscillations was not revealed.

Based on the NOAA OISST reanalysis data, the spatial structure of the Weddell Sea Front in the climatic field of the sea surface temperature was analyzed and the seasonal variability of front’s characteristics was estimated. The spatial position of the frontal zone in the Weddell Sea was analyzed using distributions of the total horizontal temperature gradient. The characteristics of the front (the position of the gradients' extrema corresponding to the front, their magnitude and temperature on the front axis) were determined for each month on the profiles of meridional and zonal temperature gradients along meridians and parallels with a discreteness of 2.5° of longitude and 0.25° of latitude. It is shown that the interaction of Weddell Sea cold waters, which are transported by currents northward along the Antarctic Peninsula coasts, with the warmer waters of the eastern shelf of the Antarctic Peninsula and the Bransfield Strait surface water causes formation of two branches of the Weddell Sea Front. These branches round from a vast shelf at the Antarctic Peninsula tip and the Joinville archipelago the south and north and are traced further east along the boundaries of the bottom rise located approximately between 62.5S and 64.5S. To the south of the South Orkney Islands shelf, the two branches merge into one front, which follows to the east along the depth dump of the relative shallow between the South Orkney and South Sandwich Islands. In the seasonal cycle of the Weddell Sea Front intensity, a time lag was revealed of the front intensification period in the direction from west to east. In Bransfield Strait the front is most intense in February, between the Antarctic Peninsula tip and the South Orkney Islands – in March, east of the South Orkney Islands – in April. The branch of the Weddell Sea Front off the northeastern of the Antarctic Peninsula coasts intensifies in November – January, in the western part of the water area east of the James Ross and Snow Hill Islands – in January – February.

The thermohaline structure of water in the Antarctic coastal areas adjoining Molodezhnaya, Novolazarevskaya, and Bellingshausen stations is analyzed using many-hour soundings carried out in March–April 2019 during the 64th Russian Antarctic Expedition on the Akademik Fedorov research vessel. Water masses typical of the Antarctic zone (Antarctic surface, Antarctic shelf, Antarctic winter, upper circumpolar deep water, Bransfield Strait surface water) are identified, and the features of their temporal variability are described. It is shown that intradaily and interdaily variations in water temperature and salinity were observed during the measurement period. The changes in the water structure in the area of Molodezhnaya, Novolazarevskaya, and Bellingshausen stations occurred under changes in synoptic atmospheric conditions, and their frequency was close to that of tidal processes.

По данным инструментальных измерений течений и гидрологических съемок, выполненных в ходе трех экспедиций на НИС «Профессор Водяницкий» в течение 2018 г., проанализированы особенности проявления синоптических вихрей в термохалинных полях в различные сезоны.Показано, что меандрирование Основного Черноморского течения ослабевало с лета к концу осениначалу зимы.Максимальное количество вихрей наблюдалось летом, минимальноев осенне-зимний период.Большинство антициклонических круговоротов в термохалинных полях более четко выявлялись на глубинах ниже ядра холодного промежуточного слоя по пониженным значениям температуры и солености.В зонах антициклонов наблюдалось заглубление ядра холодного промежуточного слоя и верхней границы сероводородной зоны.В зонах большинства циклонических круговоротов в термохалинных полях отмечались понижение температуры выше холодного промежуточного слоя и ее повышение ниже этого слоя, увеличение солености во всем слое инструментальных измерений течений, а также подъем ядра холодного промежуточного слоя и верхней границы сероводородной зоны ближе к поверхности.Положение областей вод с экстремальными значениями термохалинных характеристик, обусловленными циркуляцией вод, как правило, было смещено относительно положения вихревых образований, выявленных в результате инструментальных измерений течений.Это отражает разное время реакции динамической и термохалинной структуры вод на изменение синоптических атмосферных процессов. Кл юч евы е слова :

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Large-scale temperature fronts (polar, Spitsbergen, Arctic, and coastal) are revealed in the Barents Sea based on the data of NOAA OI SST reanalysis which contains the monthly mean values of sea surface temperature. The features of the climatic interannual cycle of their characteristics are identified.

The present work represents the results of water circulation in the northern Black Sea analyzed based on the data of the surveys carried out in the 87 th cruise of R/V Professor Vodyanitsky in July 2016.It is shown that during the survey the westward flows being the Rim Current (RC) manifestation are predominant within the studied water area.Based on the survey data, the latitudinal location of the Rim Current geostrophical deep stream is close to its climatic position.In the western part of the polygon, the Rim Current is divided into three branches.The northern branch is located over the shelf, the central one -over the continental slope and the southern one -over the deep-sea regions.The Sevastopol anticyclone is characterized by extremely asymmetric vertical development: its northern periphery over the shelf is weak, whereas the southern periphery over the continental slope is intensive.In the central part of the polygon the Rim Current intensifies, at that one intensive stream is traced.In the eastern part of the polygon two branches of the Rim Current are observed: the intensive northern one over the continental slope and the coastal shelf, and the one located closer to the deepsea regions (its velocity is rather low and it weakens moving eastward).In the upper layer to the east off Cape Ai-Todor, the anticyclonic gyre is observed; whereas within the 50-100 m below it, the cyclonic turn of the currents is revealed.