Long-term seasonal variability of water transparency in the surface layer of the deep part of the Black Sea

Abstract

Basing on the data of long-term observations of the Secchi disk visibility depth (1923–2000) and the beam attenuation coefficient (1978–1995), considered are the main peculiarities of seasonal spatial distribution of transparency and its intraannual and interannual variability in the deep part of the Black Sea. Noted is a decrease in the transparency in the late 1980s-early 1990s. Obtained are the statistic estimates of its seasonal variations for the whole water area of the sea and for cyclonic and anticyclonic eddies. It is demonstrated that the interannual seasonal variations of transparency are basically connected with the interannual dynamics of phytoplankton biomass which is defined with climatic conditions.