1. Institute of Geophysics and Meteorology; University of Cologne; Cologne Germany
2. Southwest Research Institute; San Antonio Texas USA
3. School of Electrical Engineering; Royal Institute of Technology; Stockholm Sweden
4. Department of Atmospheric, Oceanic, and Space Sciences; University of Michigan; Ann Arbor Michigan USA
5. Department of Earth and Planetary Sciences; Johns Hopkins University; Baltimore Maryland USA
6. Department of Physics and Astronomy; Johns Hopkins University; Baltimore Maryland USA
7. Max Planck Institute for Solar System Research; Göttingen Germany
8. Marshall Space Flight Center; Huntsville Alabama USA
9. School of Earth and Atmospheric Sciences; Georgia Institute of Technology; Atlanta Georgia USA