Nonextensive and distance-based entropy analysis on the influence of sunspot variability in magnetospheric dynamics
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In the present study, information theoretic distance-based entropies have been employed for a better understanding of nonlinear features of the magnetosphere using proxies such as AE and Dst indices. Among the various distance-based entropies, approximate and sample entropies are considered as potential quantifiers which could track the nonlinear variations of the magnetospheric system. The generalized nonextensive Tsallis q-entropy and Fisher’s information measure are used to study the nonextensive entropy and complexity respectively of the magnetospheric dynamics. For the analysis, 1-min AE and Dst indices are considered during the period 1985–2007. The results indicate that nonlinearity and nonextensive entropy of Dst index are solar activity dependent. But, the nonlinearity and nonextensive measures of AE index are not having any solar activity dependence. This implies that, other than the modulating solar wind, certain other complex phenomena of internal origin are having influence on the dynamics of geomagnetic activity in the auroral zone.
KeywordsInformation theory Nonextensivity Magnetospheric dynamics Sunspot variability
The authors are thankful to World Data Center for Geomagnetism, Kyoto, Japan for providing 1-min auroral index data (http://wdc.kugi.kyoto-u.ac.jp/) and to USGS for providing 1-min Dst index data (http://geomag.usgs.gov/). The authors acknowledge SIDC for providing sunspot numbers (http://www.sidc.be/silso/datafiles). Authors would also like to thank the anonymous referee for providing valuable comments and suggestions which have led to significant improvement of the quality of the manuscript.
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