1. Department of Earth's Physics, St. Petersburg State University, St. Petersburg 198504, Russia
2. Space Research Institute, Austrian Academy of Sciences, Graz 8042, Austria
3. Laboratory for Atmospheric and Space Physics (LASP), University of Colorado Boulder, Boulder, Colorado 80303, USA
4. Institute for Modeling Plasma, Atmospheres and Cosmic Dust, NASA/SSERVI, Mountain View, California 94035, USA
5. Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles à Saint Quentin, 78280 Guyancourt, France
6. Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
7. KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden