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Evaluation of spreading critical exponents from the spatiotemporal evolution of emission regions in the nighttime aurora
Author(s) -
Uritsky Vadim M.,
Klimas Alexander J.,
Vassiliadis Dimitris
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl016556
Subject(s) - self organized criticality , criticality , physics , scaling , non equilibrium thermodynamics , power law , statistical physics , polar , critical exponent , spacecraft , scaling law , geophysics , condensed matter physics , astronomy , geometry , phase transition , quantum mechanics , nuclear physics , statistics , mathematics
Recently, it has been found that the spatiotemporal evolution of auroral emission regions, as depicted by the ultraviolet imager (UVI) onboard the POLAR spacecraft, follows well‐defined power law statistical relations characteristic of complex systems near criticality [ Uritsky et al. , 2002b]. In this study, we continue our investigation of scaling features in the auroral emissions with emphasis on their dynamical characteristics. Based on an analysis of more than 6,700 emission events, we estimate the so‐called spreading critical exponents that govern the mean field evolution of localized perturbations in nonequilibrium systems with spatially extended degrees of freedom. We show that the auroral emissions display scale‐free spreading behavior that manifests itself through characteristic power‐law auroral emission area dynamics. The spreading exponents so obtained are consistent with scaling relations predicted for self‐organized criticality.