1. Instituto Nacional de Pesquisas Espaciais São José dos Campos São Paulo Brazil
2. Now at Laboratoire de Physique et Chimie de l'Environnement et de l'Espace, CNRS Orléans France
3. Jet Propulsion LaboratoryCalifornia Institute of Technology Pasadena California USA
4. The Johns Hopkins University Applied Physics Laboratory Laurel Maryland USA
5. Birkeland CenterUniversity of Bergen Bergen Norway