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| Titel |
Low frequency 1/f-like fluctuations of the AE-index as a possible manifestation of self-organized criticality in the magnetosphere |
| VerfasserIn |
V. M. Uritsky, M. I. Pudovkin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 16, no. 12 ; Nr. 16, no. 12, S.1580-1588 |
| Datensatznummer |
250013596
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| Publikation (Nr.) |
 copernicus.org/angeo-16-1580-1998.pdf |
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| Zusammenfassung |
Low frequency stochastic variations of the
geomagnetic AE-index characterized by 1/f b-like power
spectrum (where f is a frequency) are studied. Based on the analysis of
experimental data we show that the Bz-component of IMF,
velocity of solar wind plasma, and the coupling function of Akasofu are
insufficient factors to explain these behaviors of the AE-index together with
the 1/f b fluctuations of geomagnetic intensity. The effect of
self-organized criticality (SOC) is proposed as an internal mechanism to
generate 1/f b fluctuations in the magnetosphere. It is
suggested that localized spatially current instabilities, developing in the
magnetospheric tail at the initial substorm phase can be considered as SOC
avalanches or dynamic clusters, superposition of which leads to the 1/f b
fluctuations of macroscopic characteristics in the system. Using the sandpile
model of SOC, we undertake numerical modeling of space-localized and global
disturbances of magnetospheric current layer. Qualitative conformity between the
disturbed dynamics of self-organized critical state of the model and the main
phases of real magnetospheric substorm development is demonstrated. It is also
shown that power spectrum of sandpile model fluctuations controlled by real
solar wind parameters reproduces all distinctive spectral features of the AE
fluctuations.
Key words. Magnetospheric physics (MHD waves and
instabilities; solar wind · magnetosphere interactions; storms and substroms). |
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