Chatanika/Triad observations of unstable ionization enhancements in the auroral F‐region

Abstract

Preliminary results are presented from a campaign of coordinated measurements between the Chatanika radar and the TRIAD satellite to investigate production mechanisms responsible for localized high‐latitude scintillations. The radar measured the latitudinal variations of plasma density and electric field while the satellite measured the field‐aligned current distribution with latitude. This information was used to calculate the linear growth rate of the current convective instability. We find that field‐aligned ionization enhancements, which are a common feature of the auroral F‐region, are unstable, with instability growth times of ≤ 6 minutes. The observed plasma configuration, which was already gradient drift unstable on its poleward edge, was further destabilized by a field‐aligned current of ∼ 0.8 µA/m². The presence of electron density irregularities produced in the unstable region was verified by observing VHF scintillations on the TRIAD telemetry signal.