Thermohaline structure of the sea

Abstract

Results of statistical and physical analyses of the historical hydrographic data set (more than 90000 pairs of water temperature and salinity vertical profiles during 1957-1996) are presented. The thermohaline structure of the Black Sea waters consists of a few layers with different thicknesses, origins, and seasonal and interannual variabilities. It is caused by the extremely restricted external water budget, the significant differences in the salinities (and densities) of the waters that are supplied to the surface and deep layers of the sea, and the weak vertical turbulent mixing in the main water layer. In the upper 50-m layer, the seasonal and interannual variabilities of the thermohaline structure are generated by the fluxes of heat and fresh water across the sea surface; in the main pycnocline between depths of 50 and 200 m, they are caused by the flux of the wind relative vorticity, and in the underlying deep layer they are related to the Sea of Marmara waters inflow through the Bosporus Strait and the geothermal heat flow from the bottom. The thermohaline effects of these processes in all the main layers of the Black Sea are described. © 2007 Springer-Verlag Berlin Heidelberg.