1. a Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
2. b The Norwegian Water Resources and Energy Directorate, P.O. Box 5091, Majorstua, N-0301, Oslo, Norway
3. c The Norwegian Meteorological Institute, P.O. Box 43 Blindern, N-0313, Oslo, Norway
4. d Water, Energy, and Environmental Engineering Research Unit, University of Oulu, P.O. Box 4300, Oulu F-90014, Finland
5. e Swedish Meteorological and Hydrological Institute, SE-601 76, Norrköping, Sweden