Affiliation: | Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32,;Moscow, 117997, Russia and Institute of Physics, Maritime University in Szczecin, Waly Chrobrego, 1/2, 70500 Szczecin, Poland. E-mail: Fachrichtung Geophysik, Freie Universität Berlin, Malteserstr. 74-100,;Haus D, 12249 Berlin, Germany. E-mails: |