Spatial-Temporal Characteristics of Flickering Spots in Flickering Auroras

Abstract

Using video data obtained by a low-light-level TV camera, spatial-temporal characteristics of flickering spots in flickering auroras are studied. The results show that flickering spots often move in periodic fashion synchronized with their luminosity oscillations. For the examples studied here, the frequency ranges from 3 to 8Hz; the velocity of the motion of spots perpendicular to the magnetic field is in a range from 90 to 240km/s and the horizontal distance of the motion is in a range 10 to 20km, being almost equal to the size of a spot. It is shown that a lot of spots often form a cluster and that a lot of clusters are distributed along an auroral arc. It is also shown that the lifetime of a certain flickering spot is 1 to 2 seconds and that the lifetime of the cluster is tens of seconds to hundreds of seconds. On the basis of these results, a mechanism of flickering auroras is briefly discussed.