Linear gradient drift instabilities in the daytime equatorial electrojet

S. Hu, A. Bhattacharjee, B. G. Harrold

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Linear gradient drift instabilities, which are associated with type II irregularities in the equatorial electrojet, are obtained for daytime profiles using initial-value and eigenmode methods in a nonlocal theory. The methods are shown to be in agreement, thus resolving a recent discrepancy between the theories of Ronchi et al. [1989] and Wang and Bhattacharjee [1994]. A set of equilibrium profiles that are consistent with observed daytime electric and current density profiles are given and analyzed for nonlocal stability. Instabilities with horizontal wavelengths of the order of 1 km are found to be dominant over most of the electrojet, with instabilities of shorter wavelengths (of the order of 100 m) localized in regions of weak velocity shear. The predictions of linear theory are in accord with the observed preponderance of kilometer-scale irregularities in the daytime electrojet.

Original languageEnglish (US)
Article number96JA02826
Pages (from-to)337-346
Number of pages10
JournalJournal of Geophysical Research: Space Physics
Issue numberA1
StatePublished - 1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • 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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