Abstract
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 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 larger
values (17 {plus minus} 11 and 6 {plus minus} 9 mWm-2 on average on
each side of the arc) than the Joule heating obtained from more
conventionally used SuperDARN data (4.8 mWm-2). This result indicates
that high spatial and temporal resolution electric fields may play an
important role in the dynamics of the thermosphere, and thus the
ionosphere-magnetosphere system in general.