1. Sodankylä Geophysical Observatory; Sodankylä Finland
2. Department of Physical Sciences; University of Oulu; Oulu Finland
3. Department of Physics and Engineering Physics; University of Saskatchewan; Saskatoon, Saskatchewan Canada
4. Department of Physics; Alabama A&M University; Normal Alabama USA
5. Space Science Laboratory; University of California; Berkeley California USA
6. Department of Earth and Space Sciences; University of Washington; Seattle Washington USA