Assessment of the Black Sea Temperature and Salinity Climatic Fields for the Recent Climatological Period (1991–2020)
Authors: Markova N. V. ,   Marine Hydrophysical Institute, Russian Academy of Sciences, Sevastopol, Russian Federation, Belokopytov V. N. ,   Marine Hydrophysical Institute, Russian Academy of Sciences, Sevastopol, Russian Federation, Dymova O. A. ,   Marine Hydrophysical Institute, Russian Academy of Sciences, Sevastopol, Russian Federation, Miklashevskaya N. A. ,   Marine Hydrophysical Institute, Russian Academy of Sciences, Sevastopol, Russia
Published: August 2021

Purpose. The study is aimed at assessing a new climatic array of the Black Sea temperature and salinity calculated using hydrological observations for the standard (according to the World Meteorological Organization definition) 30-year climatological period 1991–2020. Methods and Results. New array of the temperature and salinity climatic fields was assessed based on analyzing the results of numerical experiments. In the experiment, annual variation of the Black Sea hydrophysical parameters was reproduced by the numerical model. Modeling included the scheme of assimilating the data of the climatic temperature and salinity array assessed. In contrast to the averaged data of the field observations, the model fields were matched from the viewpoint of the motion equations. Besides the temperature and salinity three-dimensional fields, the three-dimensional climatic fields of the Black Sea currents were also reproduced for each day of a climatic year that is quite impossible using the instrumental measurements data only. Spatial-temporal variability of the modeled three-dimensional fields was analyzed. The integral characteristics of the Black Sea water dynamics for the recent 30-year climatic period were studied and compared with the analogous ones for the previous century. Simulation was performed at the grid with the 5 km horizontal resolution using the EMODNet bathymetry by means of the three-dimensional non-linear model of the Black Sea dynamics developed in Marine Hydrophysical Institute. Having been analyzed, the performed calculations showed that the increased spatial resolution of the temperature and salinity climatic array for the recent period made it possible to reproduce dynamics in all the layers of the Black Sea waters in more details. At the same time, a significant small-scale variability, most pronounced at the deep-water horizons, was present in the salinity fields. Conclusions. As compared to the experiment with assimilation of the previous version of the climatic array, the modeling based on the new array of the thermohaline fields revealed increase in the integral temperature of the upper mixed layer. At that, thinning and «break» of the cold intermediate layer found in the central part of the sea, indicates warming of the sea upper layer during the last 30 years. The highest noisiness detected at the deep-water horizons in the modeled salinity fields is related to quantity and quality of the salinity data resulted from the field observations. Taking into account insufficient metrological facilities for measuring seawater electrical conductivity, the next version of climatic array requires a more strict procedure for verifying and processing the observation data obtained in the deep-sea layers.