1. Max Planck Institute for Solar System Research; Gottingen Germany
2. Ludwig Maximilian University of Munich; Munich Germany
3. Institute of Geology and Geophysics; Chinese Academy of Sciences; Beijing China
4. Space Research Institute; Russian Academy of Sciences; Moscow Russia
5. Space Physics Division; Belgian Institute for Space Aeronomy; Brussels Belgium
6. Birkeland Center for Space Science; University of Bergen; Bergen Norway
7. Key Laboratory of Ionospheric Environment, Institute of Geology and Geophysics; Chinese Academy of Sciences; Beijing China