Relationships between inherent optical properties in the Baltic Sea for application to the underwater imaging problem**This work was supported by the Russian Foundation for Basic Research project No. 10-05-00311. Partial support for this study was also provided by the Satellite Monitoring of the Baltic Sea Environment – SatBałtyk project, funded by the European Union through European Regional Development Fund contract No. POIG 01.01.02-22-011/09 and statutory research funds from the Institute of Oceanology PAS, Sopot