Affiliation: | 1.Sodankylä Geophysical Observatory, FIN-99600, Sodankylä, Finland ;2.Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, 123995, Moscow, Russia ;3.Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation, 108840, Troitsk, Russia ;4.Polar Geophysical Institute, 184209, Apatity, Russia ; |