Fine-scale electric felds and Joule heating from observations of the Aurora

Abstract

<p>Our goal is to research highly dynamic electric fields near auroral arcs and their effects on the thermosphere via Joule heating. Optical measurements from three selected wavelengths have been combined with modelling of emissions from an auroral event to estimate the magnitude and direction of small-scale electric fields on either side of an auroral arc. The direction of these fields was found to be towards the arc on both sides. The temporal resolution of the estimates is 0.1 seconds, which is much higher resolution than measurements from SuperDARN from the same region, with which we compare our estimates. Additionally, we have used the SCANDI instrument to measure the neutral wind during the event in order to calculate the height integrated Joule heating. Joule heating obtained from the small scale electric fields gives higher values than the Joule heating obtained from more conventionally used SuperDARN data. This result indicates that high resolution electric felds may play an important role in the dynamics of the thermosphere, and thus the ionosphere-magnetosphere system in general. Furthermore, we are aiming to combine our method with EISCAT-measured electron density profiles and high- resolution spectrographic observations of N2 auroral emissionto obtain local Joule heating profile. We will then compare it to the estimates of a local neutral temperature profiles.</p>