High temporal resolution observations of auroral electron density using superthermal electron enhancement of Langmuir waves

Abstract

We report high temporal resolution auroral electron precipitation observations using the Sondrestrom incoherent scatter radar. The observations make use of the superthermal electron enhancement of Langmuir waves, which is shown to give accurate observations of the electron density during auroral ionization at a subsecond temporal resolution. This is important when matching to the time scales of auroral precipitation-related phenomena, such as energy input into the atmosphere and magnetospheric electron acceleration mechanisms. We describe the measurement technique and show an example observation of auroral precipitation. The results show transients in electron density in the order of a few seconds, which are fully resolved by the plasma line measurements. An electron precipitation model is used to estimate precipitation energy and flux density. The energetic electron flux during the example event has variations even at short time scales. The results show that electron density profiles derived from plasma lines can be a powerful new observational capability.