Key points are not available for this paper at this time.
Auroral spirals of 20- to 1300-km diameter are a common part of the active auroral display. They appear most frequently in the evening and midnight sectors, where they appear to be produced as a consequence of magnetic field line distortion caused by field-aligned currents. More quiescent spiral forms exhibiting somewhat different characteristics occur during quiet times in the polar cap near the dawn portion of the auroral oval. (AIP)
Davis et al. (Sun,) studied this question.