[1] Univ Colorado Boulder, Lab Atmospher & Space Phys, 1234 Innovat Dr, Boulder, CO 80303 USA
[2] Univ Colorado Boulder, Natl Solar Observ, Boulder, CO 80303 USA
[3] RAS, Inst Solar Terr Phys, SB, Irkutsk, Russia
[4] Natl Ctr Atmospher Res, High Altitude Observ, Boulder, CO USA
[5] Univ Colorado Boulder, Dept Astrophys & Planetary Sci, Boulder, CO USA
[6] CSIRO, Space & Astron, Epping, NSW, Australia