Horizontal plasma flow at midlatitudes: More mechanisms and the interpretation of observations

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9 Scopus citations


The midlatitude ionosphere has been known for decades to exhibit correlated (or anticorrelated, depending on the coordinate system) perpendicular and parallel meridional ion velocities. This correlation is indicative of horizontal plasma flow, despite the highly magnetized character of the midlatitude F region. This coupling of the perpendicular and parallel dynamics is a consequence of extremely weak atmosphere-ionosphere coupling and the strong tendency for the neutral atmosphere to flow horizontally. Three physical mechanisms have previously been identified as effecting this coupling: ion drag, the F region dynamo, and enhanced gravity-driven diffusion. We point out some difficulties with one of these processes and present two additional mechanisms, wind-driven ionospheric equilibrium and gravity wave seeding of plasma instabilities, which can also result in horizontal plasma flow. Although these additional mechanisms further complicate the observational distinction between the possible mechanisms, we argue that an appropriately clustered array of instruments can still distinguish which mechanism is responsible for any particular geophysical occurrence.

Original languageEnglish (US)
Article number96JA03842
Pages (from-to)11549-11555
Number of pages7
JournalJournal of Geophysical Research Atmospheres
Issue numberA6
StatePublished - 1997
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Oceanography
  • Forestry
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Palaeontology


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