Long-term trends in variability of dissolved oxygen and salinity concentration under the cold intermediate layer of the black sea waters

by

A.A. Valle

Institute of Natural and Technical Systems, RF, Sevastopol, Lenin St., 28

E-mail: ogorodovaa.a@mail.ru

DOI: 10.33075/2220-5861-2023-4-71-77            

UDC 551.465 (262.5)                                       

EDN: https://elibrary.ru/speyxa

Abstract:

In the paper, we analyze the spatiotemporal variability of salinity and dissolved oxygen concentration based on archival data from 1924 to 2020 at a horizon of 100 m. The analysis is carried out in the area of the western and eastern gyres of the Black Sea, as well as in the area of the depth slope off the northwestern shelf. The archived data used are obtained both through ship observations and measured by ARGO profiling buoys, and accumulated in the data bank of the Institute of Natural-Technical Systems. This work is a continuation of previous work in which trends and long-term variability of salinity and dissolved oxygen concentration are analyzed at 50 and 75 m horizons.

The data are averaged over three areas: the western and eastern parts of the sea (in the vicinity of the dome-shaped rise of isooxygen related to the cyclonic circulation of the Black Sea waters, which forms two semi-closed gyres), as well as in the area of the depth slope near the northwestern shelf, where a fairly large number of measurements have been made.

Based on the analysis of the long-term variability of salinity and dissolved oxygen concentration at a 100 m horizon in the area of the western, eastern gyres and the depth slope, a conclusion can be drawn. From 1924 to 2020 there is an increase in salinity and a decrease in the dissolved oxygen concentration in the centers of the gyres and a corresponding decrease in salinity at the periphery and an increase in the dissolved oxygen concentration.

Keywords: concentration of dissolved oxygen, salinity, long-term variability, western and eastern cyclonic gyres, depth slope.

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