1. Department of Physics and Astronomy; University of Iowa; Iowa City IA USA
2. Department of Space Physics; Institute of Atmospheric Physics, The Czech Academy of Sciences; Prague Czech Republic
3. Faculty of Mathematics and Physics; Charles University; Prague Czech Republic
4. Department of Atmospheric and Oceanic Sciences; University of California, Los Angeles (UCLA); Los Angeles CA USA
5. School of Physics and Astronomy; University of Minnesota; Minneapolis MN USA
6. Space Sciences Laboratory; University of California, Berkeley; Berkeley CA USA