A note to the simulation of the annual and inter-annual variability of the water budget over the Baltic Sea drainage basin

Summary The annual and inter-annual variability of the water budget over the Baltic Sea area has been studied using the global climate model ECHAM4/T106 and the regional climate model REMO for three experiments covering a time period of 10 years each. To address the capability of REMO to simulate realistically the water budget over the Baltic Sea re-analyses data (so-called perfect boundaries) were applied as lateral boundary conditions. The validation against observations shows that the results agree rather well. However not all components of the hydrological cycle are observed, therefore only some of them could be compared to the simulation results. A clear dependence of the annual cycle of precipitation from the horizontal resolution was found in the experiments. Until now it is still unclear which processes are responsible for this. Further research will help to identify the sensitive physical processes involved in the water budget and their interactions. Received September 8, 2000 Revised April 3, 2001