1. Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire 03824, USA
2. Department of Physics and Astronomy and Center for KINETIC Plasma Physics, West Virginia University, Morgantown, West Virginia 26506, USA
3. Goddard Space Flight Center, NASA, Greenbelt, Maryland 20771, USA
4. Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA
5. Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas 78238, USA