V.A. Eremenko - Ph.D. (Phys.-Math.), Leading Research Scientist, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Science (IZMIRAN)

E-mail: eremenko@izmiran.ru

N.I. Manaenkova - Ph.D. (Phys.-Math.), Senior Research Scientist, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Science (IZMIRAN) E-mail: nat_man@mail.ru