Using multispectral optical observations to identify the acceleration mechanism responsible for flickering aurora

We present an analysis of flickering (2–10 Hz) auroras observed with a state-of-the-art multispectral imaging system, Auroral Structure and Kinetics, located in Tromsø, Norway. Short (1–2 s) periods of flickering aurora have been identified in which the frequency of the brightness oscillations decreases or increases smoothly over time. To the authors' knowledge this is the first detailed analysis of such “chirps” in flickering aurora or field-aligned bursts. We have found that the electron precipitation energy is strongly anticorrelated with the flickering frequency during all identified chirps. This result is consistent with the theory that flickering aurora is caused by the resonance interaction between electromagnetic ion cyclotron waves and precipitating electrons and that the wave parallel phase velocity is the primary factor determining the electron acceleration produced by this mechanism. Other current theories known to the authors cannot completely explain our observations.

10.1029/2010JA015805

0148-0227

A12315

Whiter, D.K.

9a30d7b6-ea41-44fb-bd52-3ff1964eca5c

Lanchester, B.S.

e864533e-eea0-471f-a3f9-7c70c25be55b

Gustavsson, B.

5ef90805-5748-4626-a3b6-85554fac934d

Ivchenko, N.

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Dahlgren, H.

8d021086-b328-46fd-affd-a7c8d2b4687e

2010