Scaling of electric field fluctuations associated with the aurora during northward IMF

Kozelov, B. V.; Golovchanskaya, I. V.

doi:10.1029/2006gl027798

Cited by 27 publications

(25 citation statements)

References 13 publications

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“…In other words, if we interpret scaling index α A as α A = 2H , we have a transition from a noisy anti-persistent (H < 0.5) signal to a smoother persistent (H > 0.5) one, in agreement with a similar result of Uritsky et al (2006) obtained from the analysis of the roughness exponent of auroral surfaces during substorms. Interestingly, Kozelov and Golovchanskaya (2006) reported a similar variation of the scaling index for auroral luminosity observed during intensification of a transpolar arc under positive IMF B z , that is, in obviously non-substorm conditions.…”

Section: Scaling Behavior Of the Aurora At Substorm Early Expansion Asupporting

confidence: 57%

Inverse cascade in the structure of substorm aurora and non-linear dynamics of field-aligned current filaments

2011

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Abstract.We investigate time evolution of scaling index α A that characterizes auroral luminosity fluctuations at the beginning of substorm expansion. With the use of UVI images from the Polar satellite, it is shown that α A typically varies from values less than unity to ∼1.5, increasing with breakup progress. Similar scaling features were previously reported for fluctuations at smaller scales from all-sky TV observations. If this signature is interpreted in terms of non-linear interactions between scales, it means that the power of smallscale fluctuations is transferred with time to larger scales, a kind of the inverse cascade. Scaling behavior in the aurora during substorm activity is compared with that in the fieldaligned currents simulated numerically in the model of nonlinear interactions of Alfvénic coherent structures, according to the Chang et al. (2004) scenario. This scenario also suggests an inverse cascade, manifesting in clustering of smallscale field-aligned current filaments of the same polarity and formation of "coarse-grained" structures of field-aligned currents.

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Section: Scaling Behavior Of the Aurora At Substorm Early Expansion Asupporting

confidence: 57%

Inverse cascade in the structure of substorm aurora and non-linear dynamics of field-aligned current filaments

2011

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“…The spatio-temporal technique (Uritsky et al, 2002;Kozelov et al, 2004) gives the uniform scaling features of avalanchelike transients during the substorm expansion phase from scales of a few square kilometers and a few seconds, up to 10 6 square kilometers and a few hours. The analysis of the PDFs and GSFs presented here shows that the features (power-law range of GSF vs. scale, evidence of the intermittence, leptokurtic shape of the PDFs, and collapse of the rescaled PDFs) of spatial auroral fluctuations on scales of 3-20 km are the same as for the non-substorm event discussed in Kozelov and Golovchanskaya (2006). This indicates that the scaling relations may represent more universal signatures of spatio-temporal complex dynamics than those pertaining to substorm-like transients in the magnetospheric plasma.…”

Section: Discussionmentioning

confidence: 85%

Spatial scaling of optical fluctuations during substorm-time aurora

Kozelov

Rypdal

2007

Ann. Geophys.

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Abstract.A study of statistical features of auroras during substorm activity is presented, emphasizing characteristics which are commonly applied to turbulent flows. Data from all-sky television (TV) observations from the Barentsburg observatory (Svalbard) have been used. Features of the probability density function (PDF) of auroral fluctuations have been examined at different spatial scales. We find that the observed PDFs generally have a non-Gaussian, heavy-tailed shape. The generalized structure function (GSF) for the auroral luminosity fluctuations has been analyzed to determine the scaling properties of the higher (up to 6) order moments, and the evolution of the scaling indices during the actual substorm event has been determined. The scaling features obtained can be interpreted as signatures of turbulent motion of the magnetosphere-ionosphere plasma. Relations to previously obtained results of avalanche analysis of the same event, as well as possible implications for the validity of self-organized criticality models and turbulence models of the substorm activity, are discussed.

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“…The relationship between the high‐latitude electric and magnetic turbulence and the Birkeland field‐aligned currents/large‐scale convection velocity shears was evidenced by Golovchanskaya et al [2006]. The turbulent properties of small‐scale electric and magnetic fields at high latitudes have recently been strongly supported by Tam et al [2005], Kozelov and Golovchanskaya [2006], and Golovchanskaya et al [2006]. Those authors demonstrated the power‐law form of the electric and magnetic field spectra, non‐Gaussian character of the probability distribution functions (PDF) of amplitudes, collapse of the re‐scaled PDFs onto a single curve and flatness in excess of 3.…”

Section: Introductionmentioning

confidence: 94%

On the seasonal variation of electric and magnetic turbulence at high latitudes

Golovchanskaya

2007

Geophysical Research Letters

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[1] High-pass filtered field measurements from the lowaltitude polar-orbiting Dynamic Explorer 2 (DE2) spacecraft are used to investigate seasonal variation in the high-latitude electric and magnetic fields on the scales from 3.8 km to 100 km. It is shown that the seasonal asymmetry has an opposite sense for the electric and magnetic components. The electric fields are by factor 3 enhanced and the magnetic fields are by factor 1.5 reduced under winter conditions as compared to summer conditions. The effect persists at very high polar latitudes, where the magnetic field lines are strongly stretched or open, so that the time required for the Alfvén-wave communication between the ionosphere of summer and winter hemispheres is very large (>1 hour) or infinite. In this case, the earlier interpretations of the seasonal effect, which suggest that the magnetospheric generator of the turbulent fields is linked by the field-aligned currents (FACs) to the high-latitude ionosphere of both hemispheres, may be not applicable. A new explanation is proposed, in which it is assumed that the FACs from the generator region close through the Pedersen current in the ionosphere of only one hemisphere, either wintertime or summertime, and through the inertial current in the front of an outgoing Alfvén wave. It is demonstrated that the values of conductances derived within such an assumption are in a reasonable agreement with observations.

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Scaling of electric field fluctuations associated with the aurora during northward IMF

Cited by 27 publications

References 13 publications

Inverse cascade in the structure of substorm aurora and non-linear dynamics of field-aligned current filaments

Inverse cascade in the structure of substorm aurora and non-linear dynamics of field-aligned current filaments

Spatial scaling of optical fluctuations during substorm-time aurora

On the seasonal variation of electric and magnetic turbulence at high latitudes

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