Conditional integration of Incoherent Scattering in relation to flickering aurora

Grydeland, T.; Gustavsson, B.; Baddeley, Lisa; Lunde, J.E.; Blixt, E. M.

doi:10.1029/2008ja013039

Cited by 6 publications

(7 citation statements)

References 27 publications

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“…Although EISCAT data will primarily show the result of the continuous nonflickering precipitation, we would expect to see more enhancement at higher altitudes if the flickering had a significant low‐energy component. Grydeland et al [2008] showed that flickering precipitation can modulate the radar backscattered power from the upper E region. Their EISCAT experiment did not record backscatter from below 130 km, so it is not known whether there were larger modulations in the lower E region.…”

Section: Resultsmentioning

confidence: 99%

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

et al. 2010

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[1] We present an analysis of flickering (2-10 Hz) auroras observed with a state-of-theart 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. Citation: Whiter, D. K., B. S. Lanchester, B. Gustavsson, N. Ivchenko, and H. Dahlgren (2010), Using multispectral optical observations to identify the acceleration mechanism responsible for flickering aurora,

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Section: Resultsmentioning

confidence: 99%

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

et al. 2010

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“…When such temporally varying precipitation enters the ionosphere, it causes excitation and ionization with different temporal response at different altitudes [ Peticolas and Lummerzheim , 2000]. In addition to temporal variation in ionization the modulated electron precipitation also leads to temporal variation electron heating, the effect of this have been observed to be a 100 K modulation of the electron temperature [ Grydeland et al , 2008].…”

Section: Introductionmentioning

confidence: 99%

Optical observations of flickering aurora and its spatiotemporal characteristics

2008

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[1] Flickering aurora is characterized by optical emissions varying in intensity with frequencies typically between 5 and 15 Hz. In this report we use high-speed narrow field-of-view imaging in white light to determine the intensity variation and the apparent motion of the flickering spots. The characteristic patterns we find are compared with the spatial patterns derived from interference between electromagnetic ion-cyclotron waves. It is found that good agreement is reached, which we argue should make a strong rejection criterion for theories of flickering aurora.

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“…These two main frequency ranges correspond broadly to the ion cyclotron frequencies of O + and H + at 1 R E (≈10 Hz and ≈100 Hz respectively). In most known cases only a small proportion of the total aurora intensity is flickering, typically 10–20 percent [ Kunitake and Oguti , 1984; Sakanoi and Fukunishi , 2004; Grydeland et al , 2008]. Previous reports of flickering aurora have almost exclusively concentrated on patches with scale sizes larger than 1 km.…”

Section: Introductionmentioning

confidence: 99%

Small‐scale structures in flickering aurora

Whiter¹,

Lanchester²,

Gustavsson³

et al. 2008

Geophysical Research Letters

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[1] A state-of-the-art multispectral imager has been used to study the flickering component of an auroral event at high spatial (40 m) and temporal (32 fps) resolution. Scale sizes for the flickering patches were found to be regularly smaller than 1 km. The typical flickering frequency observed was in the range 6 -8 Hz, although flickering patches at both lower and higher frequencies were identified. The flickering structure was correlated with the coincident non-flickering aurora, showing that although there is a temporal relationship between the two, there is no spatial correlation. These results support the theory that flickering structure is caused by interfering dispersive Alfvén waves.

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Conditional integration of Incoherent Scattering in relation to flickering aurora

Cited by 6 publications

References 27 publications

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

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

Optical observations of flickering aurora and its spatiotemporal characteristics

Small‐scale structures in flickering aurora

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