Statistical structure of 137Cs and 90Sr concentration fields in the Baltic Sea in 1977-1978

137Cs and 90Sr concentration fields are calculated for surface water and for 50 m depth using the experimental data obtained during the ''Oceanograph'' ship expedition over the Baltic Sea in 1977-1978. The radionuclide field normalized correlation functions sharply decrease and reach zero at a distance of 50-120 km. The maps of radionuclide concentration fields for the surface waters and 50 m depth with the time difference of 1-2 months permit to assess the mixing rate and its structure change. If a time interval is more than three months between ship expeditions, the problem gets more complex