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Ann. Geophys., 25, 915-927, 2007
www.ann-geophys.net/25/915/2007/
© European Geosciences Union 2007
Spatial scaling of optical fluctuations during substorm-time aurora
B. V. Kozelov1,2 and K. Rypdal2
1Polar Geophysical Institute, Apatity, Murmansk region, 184209 Russia
2Department of Physics and Technology, University of Tromsø, 9037, Tromsø, Norway
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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