1. Faculty of Mathematics and Physics Charles University Prague Czech Republic
2. Department of Space Physics, Institute of Atmospheric Physics The Czech Academy of Sciences Prague Czech Republic
3. Department of Physics and Astronomy University of Iowa Iowa City IA USA
4. Polar Geophysical Institute Apatity Russia
5. Institute of Applied Physics Russian Academy of Sciences Nizhny Novgorod Russia
6. LPC2E/CNRS Orléans Orléans France