[1] Observ Paris, Dept Rech Spatiale, DESPA, Meudon, France
[2] Univ Padua, CISAS, Ctr Studies & Activ Space G Colombo, I-35100 Padua, Italy
[3] Univ Paris 07, F-75221 Paris 05, France
[4] Tel Aviv Univ, Dept Geophys & Planetary Sci, IL-69978 Tel Aviv, Israel
[5] NASA, AMES, Moffett Field, CA 94035 USA
[6] ESA, Sci Directorate, F-75738 Paris 15, France
[7] ESTEC, Solar Syst Div, Noordwijk, Netherlands
[8] Agenzia Spaziale Italiana, Rome, Italy
[9] LPCE, Orleans, France
[10] Finnish Meteorol Inst, FIN-00101 Helsinki, Finland
[11] CSIC, IAA, Granada, Spain
[12] Univ Kent, Canterbury, Kent, England
[13] Univ Cologne, D-5000 Cologne 41, Germany
[14] Univ Oslo, N-0316 Oslo, Norway
[15] Univ Roma La Sapienza, Rome, Italy
[16] Osserv Astrofis Catania, I-95125 Catania, Italy
[17] Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria
[18] San Jose State Univ Fdn, Dept Meteorol, San Jose, CA 95192 USA