A study of the role of ion-molecule chemistry in the formation of sporadic sodium layers

Stephen C. Collins, John M.C. Plane, Michael C. Kelley, Timothy G. Wright, Pavel Soldán, Timothy J. Kane, Andrew Gerrard, Brent W. Grime, Rosie J. Rollason, Jonathan S. Friedman, Sixto A. González, Qihou Zhou, Michael P. Sulzer, Craig A. Tepley

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78 Scopus citations


Over two campaigns in 1998 and 1999, multiple sporadic sodium events were observed by the Arecibo Observatory sodium density lidar while simultaneously monitoring the plasma density using the incoherent scatter radar. In this paper, we test the theoretical explanation proposed by Cox and Plane (1998) where Na+ in a plasma layer is neutralized via an ion-molecule mechanism to form a sporadic sodium layer. A particular challenge is to interpreter observations made in a Eulerian frame of observation where the spatial and temporal characteristics of events cannot easily be separated. The reaction scheme in the original mechanism is modified to include the reactions NaO+ + N2 → Na+ .N2 + O and NaO+ + O2 → Na+ + O3, following the results of theoretical quantum calculations. Six unique case studies of sporadic sodium layers are presented here, and excellent agreement between simulation and observations was obtained for five of them.

Original languageEnglish (US)
Pages (from-to)845-860
Number of pages16
JournalJournal of Atmospheric and Solar-Terrestrial Physics
Issue number7
StatePublished - 2002

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science


  • Atmospheric composition and structure
  • Ion-molecule chemistry of the atmosphere
  • Ionosphere
  • Sodium lidar
  • Sporadic E layers
  • Sporadic sodium layers


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