Shokurova I. Long-term variability of the hydrological fields and the geostrophic circulation in the Black Sea

The interdecadal variability of the hydrologic fields and the geostrophic circulation in the Black Sea since 1950-s to the present time is examined. The temperature, salinity and density fields at the standard levels in 0-500 m layer are calculated by the optimum interpolation method using ship and remote sensing observations in the Black Sea. Statistical structure of the temperature and salinity fields is investigated by the means of calculating one-dimensional or two-dimensional correlation functions. Long-term tendencies of ten-year variability of the temperature and salinity in 1951-2008 were received. The temperature and salinity in the upper layer of the sea 0-50 m changed as long-term quasiperiodic fluctuations. They manifested positive trends in 75-500 m. Geostrophic circulation was calculated for the ten-year intervals in 1951-1995. Long-term intensification of the circulation of the sea in winter and quasiperiodic fluctuations in summer in the upper layer were received. In the layer below 150 m the circulation weakened. Increasing of the static stability in the pycnocline was obtained. Reasons of the changes are discussed.