Modeling runoff to the Baltic Sea

A large-scale hydrologic model of macroscale dimension for total daily runo ff to the Baltic Sea has been developed using 25 subbasins ranging from 210 00 to 144000 km(2). Daily synoptic input was calibrated against monthly rec orded river flows. Reasonable model results for the water balance were obta ined while keeping the level of detail to a minimum with a proven conceptua l modeling approach. Important elements of the modeled water balance are pr esented for the five main Baltic Sea drainage basins. The model is used for cooperative research with both meteorological and oceanographic modeling w ithin the Baltic Sea Experiment (BALTEX) and the Swedish Regional Climate M odelling Programme (SWECLIM). It provides off-line analysis for coupled mod el development and fills a needed role until truly coupled models become av ailable. Furthermore, the model is suitable for operational applications an d will be used to extend runoff records, fill in missing data, and perform quality checks on new observations.