Affiliation: | (1) Finnish Meteorological Institute, Geophysical Research, PO Box 503, FIN-00101 Helsinki, Finland;(2) Swedish Institute of Space Physics, PO Box 537, 751 21 Uppsala, Sweden;(3) Polar Geophysical Institute, Apatity, Russia;(4) Murmansk State Technical University, Sportivnaya 13, Murmansk, Russia |