Two-dimensional simulations of gradient-drift turbulence in the daytime equatorial electrojet

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Abstract

Two-dimensional numerical simulations of type II irregularities, attributed to gradient-drift instabilities, are carried out with observed profiles in the daytime equatorial electrojet. Earlier work has shown that these profiles are linearly unstable to gradient-drift modes with peak growth rates at wavelengths of the order of 1 km. The nonlinear evolution of these instabilities leads to saturated turbulent structures, with the linear drive at kilometer-scale wavelengths quenched by a direct energy cascade to short wavelengths that are effectively damped by velocity shear and diffusion. The saturated turbulent structures show quasi-steady 1-2 km horizontal waves, and appear to be quite isotropic in the plane perpendicular to the ambient magnetic field. The electron vertical velocity spectra, constructed from the simulation output, show 1-2 km vertical structures which are qualitatively in accord with recent high-resolution radar observations at the Jicamarca Observatory in Peru.

Original languageEnglish (US)
Article number98JA01560
Pages (from-to)20749-20759
Number of pages11
JournalJournal of Geophysical Research: Space Physics
Volume103
Issue numberA9
StatePublished - Jan 1 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

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

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