Current convective instability in the diffuse aurora

Abstract

A stable E × B gradient drift geometry can become destabilized by a current along the magnetic field. This type of instability is generically called the current convective instability. This instability may be responsible for the diffuse auroral scintillation causing F region irregularities observed by the DNA Wideband satellite. In these phenomena the northward TEC gradient dominates the altitude electron density gradient. We have investigated a simple plasma fluid model and found that instability results for − k · V d > k · (c E o /B o ) ( ν i /Ω i ) where V d is the relative drift (precipitation current) between ions and electrons along B o , E o is the westward ambient electric field (⊥B o ), and ν i and Ω i are the F region ion‐neutral collision frequency and ion gyrofrequency.