Investigating dynamical complexity in the magnetosphere using various entropy measures

Georgios Balasis, Ioannis A. Daglis, Constantinos Papadimitriou, Maria Kalimeri, Anastasios Anastasiadis, Konstantinos Eftaxias
<span title="2009-06-10">2009</span> <i title="American Geophysical Union (AGU)"> <a target="_blank" rel="noopener" href="" style="color: black;">Journal of Geophysical Research</a> </i> &nbsp;
The complex system of the Earth's magnetosphere corresponds to an open spatially extended non-equilibrium (input -output) dynamical system. The non-extensive Tsallis entropy has been recently introduced [Balasis et al. (2008) , Geophys. Res. Lett., 35, L14102, doi:10.1029/2008GL034743] as an appropriate information measure to investigate dynamical complexity in the magnetosphere. The method has been employed for analyzing D st time series and gave promising results, detecting the complexity
more &raquo; ... imilarity among different physiological and pathological magnetospheric states (i.e., pre-storm activity and intense magnetic storms, respectively). This paper explores the applicability and effectiveness of a variety of computable entropy measures (e.g. Block entropy, Kolmogorov entropy, T -complexity and Approximate entropy) to the investigation of dynamical complexity in the magnetosphere. We show that as the magnetic storm approaches there is clear evidence of significant lower complexity in the magnetosphere. Overall, Approximate entropy and Tsallis entropy yield superior results for detecting dynamical complexity in the magnetosphere in comparison to the other entropy measures presented herein. Ultimately, the analysis tools developed in the course of this study for the treatment of D st index can provide convenience for space weather applications.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="">doi:10.1029/2008ja014035</a> <a target="_blank" rel="external noopener" href="">fatcat:qkcr53ddxzd7xmpzsoxh4v7wx4</a> </span>
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