Irina Zakharenkova, University of Warmia and Mazury in Olsztyn, Space Radio-Diagnostics Research Centre, Olsztyn, Poland; IZMIRAN RAS, Kaliningrad, Kaliningrad, Russia, Iurii Cherniak, University Corporation for Atmospheric Research, Boulder, United States and Paul Prikryl, University of New Brunswick, Physics Department, Fredericton, NB, Canada; Natural Resources Canada, Geomagnetic Laboratory, Ottawa, ON, Canada