1. Swedish Institute of Space Physics Uppsala Sweden
2. Institute of Atmospheric Physics Prague Czech Republic
3. Faculty of Mathematics and PhysicsCharles University Prague Czech Republic
4. Department of Physics and AstronomyUniversity of Calgary Calgary Alberta Canada
5. Laboratoire de Physique des PlasmasEcole Polytechnique Palaiseau France
6. Institute of Geophysics and Planetary Physics/Earth and Space SciencesUniversity of California Los Angeles California USA