Modeling runoff to the Baltic Sea

A large-scale hydrologic model of macroscale dimension for total daily runoff to the Baltic Sea has been developed using 25 subbasins ranging from 21000 to 144000 km(2). Daily synoptic input was calibrated against monthly recorded river flows. Reasonable model results for the water balance were obtained while keeping the level of detail to a minimum with a proven conceptual modeling approach. Important elements of the modeled water balance are presented for the five main Baltic Sea drainage basins. The model is used for cooperative research with both meteorological and oceanographic modeling within the Baltic Sea Experiment (BALTEX) and the Swedish Regional Climate Modelling Programme (SWECLIM). It provides off-line analysis for coupled model development and fills a needed role until truly coupled models become available. Furthermore, the model is suitable for operational applications and will be used to extend runoff records, fill in missing data, and perform quality checks on new observations.