1. Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece;
2. Bjerknes Centre for Climate Research, Geophysical Institute, University of Bergen, Bergen, Norway;
3. Climate Service Center Germany (GERICS)/Helmholtz-Zentrum Hereon, Hamburg, Germany;
4. Laboratoire d’Aérologie, Université de Toulouse III Paul Sabatier, CNRS, Toulouse, France;
5. Instituto de Física de Cantabria, CSIC–Universidad de Cantabria, Santander, Spain;
6. Rossby Centre, Swedish Meteorological and Hydrological Institute, Norrköping, Sweden