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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 29, issue 8
Ann. Geophys., 29, 1349–1354, 2011
https://doi.org/10.5194/angeo-29-1349-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 29, 1349–1354, 2011
https://doi.org/10.5194/angeo-29-1349-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.

ANGEO Communicates 09 Aug 2011

ANGEO Communicates | 09 Aug 2011

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

B. V. Kozelov, I. V. Golovchanskaya, and O. V. Mingalev B. V. Kozelov et al.
  • Polar Geophysical Institute, Academgorodok, 26, Apatity, Murmansk region, 184209 Russia

Abstract. We investigate time evolution of scaling index αA 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 αA 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 small-scale 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 field-aligned currents simulated numerically in the model of non-linear interactions of Alfvénic coherent structures, according to the Chang et al. (2004) scenario. This scenario also suggests an inverse cascade, manifesting in clustering of small-scale field-aligned current filaments of the same polarity and formation of "coarse-grained" structures of field-aligned currents.

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