Equatorial spread-F initiation: Post-sunset vortex, thermospheric winds, gravity waves

Erhan Kudeki, Ahmed Akgiray, Marco Milla, Jorge L. Chau, David L. Hysell

Research output: Contribution to journalArticlepeer-review


We present experimental evidence and modeling results which indicate that eastward thermospheric wind is the primary controlling factor of equatorial spread-F initiation in the post-sunset ionosphere. Eastward wind-driven Pedersen currents are able to polarize F-region density perturbations with westward tilting wavefronts into rapidly growing modes to trigger the formation of spread-F bubbles. The described process is so rapid that seeding requirements of spread-F initiation by external factors such as gravity waves are effectively eliminated.

Original languageEnglish (US)
Pages (from-to)2416-2427
Number of pages12
JournalJournal of Atmospheric and Solar-Terrestrial Physics
Issue number17-18
StatePublished - Dec 2007


  • Current systems
  • Equatorial ionosphere
  • Ionospheric dynamics
  • Ionospheric irregularities
  • Plasma waves and instabilities

ASJC Scopus subject areas

  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science


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