Increase of Temperature and Salinity in the Active Layer of the North-Eastern Black Sea from 2010 to 2020

O. I. Podymov✉, A. G. Zatsepin, V. V. Ocherednik

Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russian Federation

✉ e-mail: huravela@yahoo.com

Abstract

Purpose. The paper is aimed at assessing salinity and temperature variability in the upper 300-meter layer of the northeastern part of the Black Sea based on the analysis of the archival and modern expeditionary data.

Methods and Results. The data on the cross-sections “coast – sea center” (with the length of 70–110 nautical miles) performed from 1999 to 2009, as well as the results of regular ship monitoring in the shelf-slope zone of the northeastern part of the Black Sea carried out in 2010–2020 were used. It was found that salinity was progressively increasing in the upper 200-meter layer during the last decade. Salinity increase, on the average, constituted annually about 0.05–0.06 PSU. An increase of temperature was also observed below the layer of temperature minimum (core of the cold intermediate layer). In particular, the lower 8.7 °C isotherm rose annually, on the average, by 11 m from its annual average depth 242 m in 2010 up to 121 m in 2020. Salinity growth led to the corresponding changes in water density that resulted in elevation of the lower boundary of the oxygen-containing layer (potential density is 15.8) from the depth of 143 m in 2010 to 124 m in 2020.

Conclusions. Climatic changes have led to a noticeable salinity increase in the upper 200-meter layer of the northeastern Black Sea, as well as to a temperature increase in the layers situated below the temperature minimum layer. Though the measurements were carried out in a certain area of the shelf-slope zone, there are reasons to assume that the observed dynamics can be attributed to the entire Black Sea. Physical reasons for the observed changes require a detailed research.

Keywords

Black Sea, salinity, temperature, climatic changes

Acknowledgements

The study was carried out within the framework of the state task No. 0149-2019-0014 (expeditions and data collection) and with the support of the RFBR grant No. 20-05-00167 (processing and analysis).

Original russian text

Original Russian Text © O. I. Podymov, A. G. Zatsepin, V. V. Ocherednik, 2021, published in MORSKOY GIDROFIZICHESKIY ZHURNAL, Vol. 37, Iss. 3, pp. 279-287 (2021)

For citation

Podymov, O.I., Zatsepin, A.G. and Ocherednik, V.V., 2021. Increase of Temperature and Salinity in the Active Layer of the North-Eastern Black Sea from 2010 to 2020. Physical Oceanography, 28(3), pp. 257–265. doi:10.22449/1573-160X-2021-3-257–265

DOI

10.22449/1573-160X-2021-3-257–265

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