1. School of Physics and Astronomy; Queen Mary University of London; London UK
2. Space and Atmospheric Physics Group, Blackett Laboratory; Imperial College London; London UK
3. Electrical and Computer Engineering Department; Virginia Tech; Blacksburg VA USA
4. National Oceanic and Atmospheric Administration; Boulder CO USA
5. Department of Earth, Planetary, and Space Sciences; University of California; Los Angeles CA USA
6. Department of Mechanical Engineering and Center for Space Physics; Boston University; Boston MA USA