PECULIARITIES OF THE MERIDIONAL DISTRIBUTION AND TEMPORAL VARIABILITY OF SURFACE TEMPERATURE AND SALINITY IN THE WESTERN PART OF THE BLACK SEA DURING 1998–2000
Authors: Belevich R. R. , Andrianova O. R. , Batyrev O. A. 
Published: July 2024

Problem Statement and Purpose. The evaluation of thermohaline parameters of the seawater is the most accessible indicator of the variability of processes and the determination of trends in their development. The use of observations of the temperature and salinity of the surface layer of water, obtained by their continuous registration from the board of a specially equipped vessel, allows for obtaining a detailed picture of the statistical variability along the direction of movement and characteristics of the hydrological structures found on the way. The continuous recording of the seawater surface layer’s temperature and salinity is progress in the development of modern oceanology in comparison with the existing point measurements. The purpose of our research is to evaluate the features of the distribution of temperature and salinity of surface waters along the meridian and their temporal variability in the western part of the Black Sea in 1998–2000 along the entire route from the port of Odesa to the Bosphorus Strait.
Data & Methods. The basis for the research was the data of continuous registration of the surface layer seawater's temperature and salinity on the Odesa-Istanbul route and back during 30 months (from 3.05.1998 to 25.10.2000). The data was obtained during the ship's 172 commercial voyages scientific and research vessel "Georgiy Ushakov", which was equipped with a stationary system of continuous recording of thermohaline parameters. The distance between these points was approximately 600 km and about 1,500 values of temperature and salinity of the seawater’s surface layer were obtained. According to the calculated average monthly values of temperature and salinity of the surface layer of water on the quasi-meridional route from Odesa to the Bosphorus Strait for 1998–2000. The space-temporal variability was estimated for the average monthly values of the seawater surface layer's temperature and salinity on the quasi-meridional route from Odesa to the Bosphorus Strait for 1998–2000 years. A modern electronic climate array of the Black Sea water's thermohaline characteristics for 1991–2020 was used for comparison.
Results. The calculated average temperature for 3 years was 14.84 °C, salinity 16.98‰, and the average annual fluctuations did not exceed 0.1 of the characteristic value. In the latitudinal distribution of the characteristics, there are differences between the northern and southern parts of the sea: the increase in the spring-summer period of the average monthly temperature occurs synchronously, and the decrease – asynchronously in the autumn-winter period (the maximum warming lasts for 1.5 months on the Turkish coast); in the northern part of the third section, water with reduced salinity values (15–16‰) is occupied, and the water in 2/3 of the southern part has a salinity of 17–18‰ and higher (the amplitude of the salinity’s fluctuations in the NWBS is 3 times greater). The minimum water cooling occurs in January-February (near the Turkish coast – 6–7 °C, near the northern coast – up to 2 °C); the minimum salinity is in May (15.96–16.30‰), and the maximum in November and February (17.59–17.79‰). An inverse relationship was obtained between fluctuations in salinity and flow rates of the Danube (maximum between 44.5 and 45.5°N with a lag of flow rates of 1 month). The region has been identified on the route between 42° and 44°N that retains its characteristics throughout the year acquired during the period of autumn-winter convection. Also, according to the distribution of salinity along the route, 4 regions were identified that represented frontal and gradient zones: the Bosphorus (between 41.25 and 42.0°N), the open sea area (between 44 and 45°N), the Dniester (between 45–46°N) and Dneprobugsky (between 46 and 46.5°N).