The results of hydrological and hydrooptical measurements carried out in the spring (April 22–May 17) and summer (July 29–August 10) 2021 in the north-eastern part of the Black Sea during cruises 116th and 117th of the R/V Professor Vodyanitsky are presented. It is shown that in spring, when there was an intensive rivers run-off, the area with a high content of total suspended matter was a strip up to 40 km wide, stretched along the coast of the Krasnodar Krai. In summer, when the river run-off was weakened, the maximum values of the total suspended matter concentration were noted in a relatively narrow coastal strip no more than 20 km wide. Maximum turbidity was noted in the surface layer in spring and in summer it descended into the layer of seasonal thermocline, halocline and pycnocline. The consistency of the horizontal distributions of the total suspended matter concentration and temperature had a significant level deeper than the seasonal thermocline – in the spring in the layer from 20 to 35 m, in the summer in the layer from 15 to 70 m, while a direct correlation was observed, i.e. at these depths, warmer waters were characterized by increased turbidity. The maximum level of consistency between the horizontal fields of the total suspended matter concentration, salinity and density in spring was observed in the upper 20–25 m layer, while the correlation was inverse, i.e. at these depths, less saline and denser waters were characterized by increased turbidity, which is explained by intensive river run-off. In summer, the nature of the correlation was preserved, and the best consistency of the horizontal fields of the total suspended matter concentration, salinity and density was observed in the surface 10-m layer and deeper than the seasonal halocline and pycnocline in the 20–40 m layer.
Based on the results of hydrological and hydrooptical measurements carried out in the winter of 2020 (November 27 – December 16) off the Crimea coast during the 115th cruise of the R/V Professor Vodyanitsky, the vertical structure of the coefficients of linear relationships between the horizontal distributions of temperature, salinity, density and total suspended matter concentration with a discreteness of 1 m in depth was analyzed. It is shown that the closest linear correlation are founded between temperature, salinity and total suspended matter concentration within the upper quasihomogeneous layer. In this layer, the values of the correlation coefficients between these parameters have a negative sign and exceed 0,75 in absolute value. Below the upper quasi-homogeneous layer, in the layer of high vertical gradients of thermohaline parameters, these connections noticeably weaken, while in the temperature and density fields they change sign and become positive. At the depths of the cold intermediate layer, linear connections increase again. The estimates of the relationships between the distribution of the fluorescence intensity of phycocyanin and phycoerythrin with thermohaline parameters revealed in most cases a low correlation level. A high direct correlation with the values of R ~ 0,65 – 0,75 was revealed only between the distributions of the phycocyanin fluorescence intensity and the temperature distribution under the main thermocline in the 65 – 70 m layer.
The results of hydro-hydro-optical measurements performed in the spring of 2019 in the northern part of the Black Sea off the coast of the Crimea and the Caucasus are presented. It is shown that the maximum concentration of total suspended matter was observed off the coast of the Kerch Peninsula and in the Feodosiya Gulf, which was associated with the coastal transport of the Rim Current of freshened and turbid Azov Sea waters from the Kerch Strait. Minimums of the concentration of total suspended matter were observed at the southern boundary of the polygon in the area of the cyclonic gyre identified by the survey data, and in the southwestern part of the polygon, where the cyclonic meander was recorded. In the vertical structure of the concentration of total suspended matter in the upper 200-meter layer, three main maximums were observed, the depth of which is associated with the features of the circulation and thermohaline waters structure. One maximum was observed in the layer of seasonal thermocline and pycnocline in the eastern part of the polygon. The second maximum was traced below the cold intermediate layer core in the layer of the main pycnocline and halocline in the central part of the polygon at stations located on the periphery of the cyclonic gyre. The third maximum was found in the entire area of the polygon under the main pycnocline and halocline in the sub-oxygen zone.
The results of hydrological and hydro-optical researches carried out in the autumn of 2018 in the Black Sea northern part off the coast of the Crimea and the Caucasus are presented. The features of the spatial distribution of the total suspended matter and their relationship with hydrological parameters are revealed. It is shown that the minimum concentration of the total suspended matter was observed in the western part of the study area. An increase in the concentration of total suspended matter was noted off the coast of the Caucasus, which is associated with the alongshore transport of the Rim Current of turbid and freshened waters of numerous rivers (Rioni, Inguri, etc.). The highest concentrations of suspended matter were found in the coastal zone to the south of the Kerch Peninsula due to the agitation of the bottom and coastal suspensions under the influence of storm conditions. The vertical structure of the concentration of total suspended matter was characterized by a well-pronounced maximum, the depth of which was close to the depth of maximum vertical gradients of temperature and density. The greatest depths of maximum concentration of suspended matter and vertical temperature gradients (40–45 m) were observed to the west of the Heraclean Peninsula in the anticyclonic gyre, the minimum (up to 5–10 m) – in the open deep-sea survey part closer to the central parts of the large-scale Eastern cyclical gyre.
Based on the daily means values of surface temperature and remote sensing reflectance coefficient Rrs(555), monthly mean values of chlorophyll "a" concentration from the array of satellite measurements with high spatial resolution COPERNICUS, monthly mean temperature and salinity values of the climatic hydrological oceanographic database created at the Marine Hydrophysical Institute and calculated geostrophic current velocities are analyzed regional features of the spatial distribution of the monthly average climatic values of these parameters off the coast of the Crimea. The patterns of Rim Current manifestation in the bio-optical and thermohaline fields are revealed. Shown, that maximum propagation of water transported by Rim Current to the west in climatic fields of bio-optical and thermohaline parameters is observed in February. Rim Current manifestation in bio-optical and thermohaline fields in the form of "tongues" water with increased values of temperature, chlorophyll "a" concentration and Rrs(555) coefficient and decreased salinity values, most clearly expressed to the west of the Crimean Peninsula.
The results of hydro-optical investigations performed in the spring-summer period of 2017 in the northern part of the Black Sea are considered. It is shown that during the spring survey (22.04.17 - 6.05.17), low concentrations of the total suspended matter were observed in the surface layer. The subsurface maximum in the vertical distributions of the total suspended matter concentrations was not present. In summer (14.06.17 - 4.07.17), due to intensive coccolithophore bloom, a higher content of suspended particles was observed. It was found that in summer the vertical structure of the total suspended matter concentration was characterized by a well-pronounced maximum at the depth close to the depth of vertical temperature and density gradients maxima.
On the basis of daily means of sea surface temperature, concentration of chlorophyll "a", diffuse attenuation coefficient Kd(490) and remote sensing reflectance Rrs(555) from the array of satellite measurements with high spatial resolution COPERNICUS spatial-temporal features of seasonal and inter-annual variability of these parameters on the Black Sea surface analyzed. Shown, that in 2017, the main maximums of the Chl-a concentration and the coefficients of diffuse attenuation Kd(490) were observed in November-December. The second maximum of Chl-a and Kd(490) in the northern coastal zone of the sea was observed from February to June, in the in the deep sea – from February to March, near the sea southern coasts – from February to April. The main maximum of remote sensing reflectance Rrs(555) was observed in June-July. Shown, that in 2017 the sea surface temperature was higher than the climatic norm, the largest anomalies were observed mainly on the northwestern shelf and in the zone of the Eastern large-scale cyclonic gyre. Anomalies of Chl-a and Kd(490) during the year were predominantly negative, and the appearance of positive anomalies was observed in April to the west and to the east from the Crimean coasts. The Rrs(555) values for almost the whole year were close to the climatic norm except for June, when they were several times higher than climatic values.
By the beam attenuation measurements in the photic layer of the Black Sea the total suspended matter (TSM) content was calculated. The main features of the TSM spatial distribution were identified. The relationship between the TSM vertical distribution and the thermohaline structure is shown.
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