Shock-Induced Proton Aurora: Five Case Studies

W.S. Lewis, J L. Burch, S.B. Mende, H.U. Frey, T.J. Immel


The shock-induced proton aurora, observed in Doppler-shifted Lyman alpha with
the IMAGE FUV Spectrographic Imager, is characterized by the same general
features and behavior that have been reported in recent studies of the aurora
that is produced primarily by precipitating electrons. Typical features include
(1) a sudden, short-lived dayside brightening, covering over several hours of
local time and often extending over a wide latitude range, coincident with the
storm sudden commencement/sudden impulse; (2) subsequent instantaneous
brightening of the entire oval or a rapid propagation of enhanced luminosity
from the dayside to the nightside; (3) a thickening and poleward expansion of
the oval; and (4) shrinking of the polar cap. Comparison of the proton emission
pattern with the distribution of OI emissions observed at 135.6 nm with the
FUV/SI13 channel allows differences between the proton and electron components
of the shock-induced aurora to be distinguished. In one of the cases presented,
the dayside cusp and a localized emission feature at the polar cap boundary are
observed to move in local time in concert with one another in response to a
strong variation in IMF By.

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Presentation, Fall Meeting, American Geophysical Union, San Francisco, USA, 
8-12 December 2003