1. Institute of Solar-Terrestrial Physics of the Siberian Branch of Russian Academy of Sciences, PO Box 291, Irkutsk 664033, Russia
2. School of Sciences, University of Southern Queensland, Queensland 4350, Australia
3. Department of Applied Mathematics, Nizhny Novgorod State Technical University n.a. R.E. Alexeev, Nizhny Novgorod 603950, Russia