Thermohaline structure

In this chapter, we present the principal large-scale features of the thermohaline structure of the Black Sea waters and their seasonal and interannual variabilities. To a great degree, they define the condition and functioning of other components of the Black Sea ecosystem, in particular the general circulation and chemical properties of the waters and marine flora and fauna. 

Filippov [4] devoted to the geographical and physical descriptions of the ther-mohaline regime of the Black Sea waters. The monograph by Blatov et al. [5] plays a special role in the development of the concepts about the variability of the thermohaline structure of the Black Sea waters and its reasons. For the first time, it presented a systematic quantitative description of the processes of the climatic, seasonal, interannual, synoptic, and short-period variabilities of the temperature and salinity of the Black Sea waters in all the principal layers and regions of the sea. Most of them found their physically justified interpretations. Subsequent refinements of the parameters of the thermohaline regime of the Black Sea waters were generalized in [6-8]. 

This study differs from the latter monographs [6,8] by a significantly (1.5-to twofold) greater amount of the measurement data used and updated technology for their processing and analysis [1]. This allows one to refine and supplement the existing concepts about the Black Sea thermohaline structure. 

The features of the thermohaline structure of the Black Sea waters represent the clear manifestations of the uniqueness of its nature on the whole. Most of them are related to the very restricted water exchange of the Black Sea with the adjacent parts of the World Ocean (the Sea of Marmara and the Sea of Azov), because of which its external water budget is generally small [33]. 

The sulfide vertical distribution correlates with vertical distributions of temperature, salinity, and density in the Black Sea. As a consequence, the H2S vertical distribution vs. salinity (Fig. 3a) and temperature (Fig. 3b) is consistent with the 9 -S curve (Fig. 3b). It is evidence that the thermohaline structure of the water column controls the vertical distribution of hydrogen sulfide in the basin [27]. Physical mixing processes dominate over the in situ sulfide production. Identifiable on the 0 -H2S and S-H2S diagrams, the boundaries of three water masses in the anoxic water column correspond strictly to the boundaries on the 0 -S diagram (Fig. 3b). The temperature-salinity relationship in the Black Sea is a result of large-scale external factors such as water and heat balance of the basin. 

The main distinctive property of the Black Sea is its inland location and high isolation from the World Ocean. Because of this, formation of the sea hydrological regime and water structure is governed by the outer factors the fluxes of heat, moisture and wind stress via the sea surface, as well as the river runoff. In this connection, the sea is characterized by a high level of its environmental variability. At the same time in different parts of the Black Sea, the influence of the outer factors is very unequal. Therefore, these factors exert a different impact on the formation of hydrological fields and vertical thermohaline structure in the sea. All this confirms the necessity for... 

Consideration of the thermohaline structure of the Black Sea provides new results on the statistical and physical analysis of the historical data of ship-borne observations of the vertical profiles of the temperature and salinity of the waters. The general features of the vertical thermohaline structure of the Black Sea waters, the seasonal and interannual variabilities of the horizontal structure of the temperature and salinity in all the main water layers are described. The relations of the large-scale features of the hydrology of the Black Sea waters to external forcing (heat and moisture fluxes across the water surface, river mouths and straits, fluxes of the momentum and relative vorticity of wind) are shown. The generalization of the results of the studies of the T,S-structure of the Black Sea waters and of its seasonal and interannual variability allows the following conclusions to be made. 

Paka, V. T, 1996. Thermohaline structure of the waters over the cross sections in the Slupsk Channel of the Baltic Sea in spring, 1993. Okeanologiya (Engl. Transl.), 36, 188-198. 

What are the physical mechanisms responsible for the variability of the vertical thermohaline structure in the deep western basin As hypothesized in [1, 18], there are two major concurrent mechanisms, which can be referred to as the convective and advective mechanisms. The former is related to the evaporation from the... 

Indeed, the eastern basin water intrusions into the western basin can often be clearly identified by means of TS (temperature-salinity) analysis. In many TS diagrams, the eastern basin water (EBW) can be seen as a distinct water type, whose mixing with the local western water type accounts for the observed spanning ranges of temperature and salinity. An illustrative example is shown in Fig. 8, corresponding to the fall of 2003. In this case, the complexity of the thermohaline structure in the western basin can be explained by the intermixing of three basic... 

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