1. Department of Astronomy; Boston University; Boston Massachusetts USA
2. Center for Space Physics; Boston University; Boston Massachusetts USA
3. Planetary Environments Laboratory; NASA Goddard Space Flight Center; Greenbelt Maryland USA
4. Atmospheric, Oceanic and Space Sciences Department; University of Michigan; Ann Arbor Michigan USA
5. Laboratoire Atmosphère, Milieux et Observations Spatiales; Institut Pierre-Simon Laplace; Paris France
6. Institute of Geophysics and Planetary Physics; University of California; Los Angeles California USA
7. Laboratory for Atmospheric and Space Physics; University of Colorado Boulder; Boulder Colorado USA