Low frequency 1/f-like fluctuations of the AE-index as a possible manifestation of self-organized criticality in the magnetosphere

V. M. Uritsky, M. I. Pudovkin
1998 Annales Geophysicae  
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more » ... gers, des laboratoires publics ou privés. Low frequency 1/f-like fluctuations of the AE-index as a possible manifestation of self-organized criticality in the magnetosphere V. M. Uritsky, M. I. Pudovkin To cite this version: V. M. Uritsky, M. I. Pudovkin. Low frequency 1/f-like fluctuations of the AE-index as a possible manifestation of self-organized criticality in the magnetosphere. Abstract 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 B zcomponent of IMF, velocity of solar wind plasma, and the coupling function of Akasofu are insucient factors to explain these behaviors of the AE-index together with the 1/f b¯u ctuations of geomagnetic intensity. The eect of self-organized criticality (SOC) is proposed as an internal mechanism to generate 1/f b¯u ctuations 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¯u ctuations of macroscopic characteristics in the system. Using the sandpile model of SOC, we undertake numerical modeling of spacelocalized 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¯uctuations controlled by real solar wind parameters reproduces all distinctive spectral features of the AE¯uctuations.
doi:10.1007/s005850050726 fatcat:g25wvsnyhzeprbq7zcw3i4oo2e