[1] George Mason Univ, Sch Phys Astron & Computat Sci, Fairfax, VA 22020 USA
[2] NASA, Goddard Space Flight Ctr, Heliospher Sci Lab, Greenbelt, MD 20771 USA
[3] Univ Massachusetts, Ctr Atmospher Res, Lowell, MA 01854 USA
[4] Lowell Digisonde Int LLC, Lowell, MA 01854 USA