1. Department of Electrical and Computer Engineering Democritus University of Thrace Xanthi Greece
2. Laboratory for Atmospheric and Space Physics University of Colorado Boulder Boulder CO USA
3. Retired from Space Sciences Laboratory University of California Berkeley CA USA
4. Johns Hopkins University Applied Physics Laboratory Laurel MD USA
5. School of Space and Environment Beihang University Beijing China
6. Space Sciences Department The Aerospace Corporation El Segundo CA USA
7. Department of Atmospheric and Oceanic Sciences University of California Los Angeles CA USA