1. Space Research Institute, Russian Academy of Sciences, Moscow 117997, Russia
2. Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, Troitsk 108840, Russia
3. Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg 620137, Russia
4. Geophysik und extraterrestrische Physik, Technische Universität Braunschweig, Braunschweig 38092, Germany