1. Physics Department, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Belo Horizonte, MG 31270-901, Brazil
2. Institute of Astrophysics, FORTH, GR-71110 Heraklion, Greece
3. Department of Physics, University of Crete, GR-70013 Heraklion, Greece
4. INAF, Osservatorio Astrofisico di Catania, via S. Sofia, 78, I-95123 Catania, Italy
5. European Centre for Medium-Range Weather Forecasts, Reading RG2 9AX, UK