1. Universitá degli Studi di Torino Torino Italy
2. International Max Planck Research School on Earth System Modelling Hamburg Germany
3. Department of Environmental Sciences Copernicus Institute, Utrecht University Utrecht The Netherlands
4. Institute of Atmospheric Sciences and Climate, Consiglio Nazionale delle Ricerche Torino Italy
5. Laboratoire de Météorologie Dynamique, Institut Pierre-Simon Laplace, Ecole Normale Supérieure Paris France