Flickering aurora

spaceweb@oulu.fi - last update: 14 November 1998, 2200 UT (RR)

Flickering aurora has been described as laterally vibrating columns with synchronous periodic changes in light intensity when viewed from the side or as flickering spots when viewed at magnetic zenith (Kunitake and Oguti, 1984). The precipitating ~30 keV electron population is modulated with a frequency, about 2-20 Hz, that is much higher than what is found in typical pulsating aurora (e.g., McFadden et al., 1987). This precipitation is embedded within discrete auroral region, i.e., arcs, which also separates the phenomena from pulsating aurora.

It has been shown that the modulation is caused by electromagnetic oxygen cyclotron (EMIC) wave propagating from the auroral parallel-electric-field acceleration region at about 1 Re altitude (Temerin et al., 1986, 1993).

References

Kunitake, M. and T. Oguti, Spatial-temporal characteristics of flickering spots in flickering auroras, J. Geomagn. Geoelectr., 36, 121, 1984.
McFadden, J. P., C. W. Carlson, M. H. Boehm, and T. J. Hallinan, Field-aligned electron flux oscillations that produce flickering aurora, J. Geophys. Res., 92, 11133-11148, 1987.
Temerin, M., J. McFadden, M. Boehm, C. W. Carlson, and W. Lotko, Production of flickering aurora and field-aligned electron fluxes by electromagnetic ion cyclotron waves, J. Geophys. Res., 91, 5769, 1986.
Temerin, M., C. Carlson, and J. P. McFadden, An acceleration of electrons by electromagnetic ion cyclotron waves, in Auroral plasma dynamics, Geophysical Monograph 80, AGU, 1993.