1. Department of Environmental Sciences, University of Siena, Via Mattioli 4, 53100 Siena, Italy, Meteorological Service of Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4, Canada, and Aquatic Systems Research Unit, EULA-Chile Environmental Sciences Centre, University of Concepción, Chile, Casilla 160 - C, Concepción, Chile