Abstract
The source of diffuse aurora has been widely studied and linked to
electron cyclotron harmonic (ECH) and upper-band chorus (UBC) waves. It
is known that these waves scatter 100s of eV to 10s of keV electrons
from the plasma sheet, but the relative contribution of each wave type
is still an open question. In this paper, we report on a new structured
diffuse aurora feature observed on March 15, 2002 that could help
further our understanding. This feature is characterized by four phases:
(1) the initial phase exhibiting regular diffuse aurora, (2) the
brightening phase, where a stripe of diffuse aurora rapidly brightens,
(3) the eraser phase, where the stripe dims to below its initial state,
and (4) the recovery phase, where the diffuse aurora returns to its
original brightness. Using a superposed epoch analysis of 22 events, we
calculate the average recovery phase time to be 20 seconds, although
this varies widely between events. We hypothesize that the process
responsible for these auroral eraser events could be an interaction
between ECH and chorus waves.