Jensen-Shannon Complexity and Permutation Entropy Analysis of Geomagnetic Auroral Currents

In this study we determine whether auroral westward currents can be characterized by low-dimensional chaotic attractors through the use of the complexity-entropy methodology developed by Rosso et al. (2007, https://doi.org/10.1103/PhysRevLett.99.154102) and based on the permutation entropy developed by Bandt and Pompe (2002, https://doi.org/10.1103/PhysRevLett.88.174102). Our results indicate that geomagnetic auroral indices are indistinguishable from stochastic processes from time scales ranging from a few minutes to 10 hr and for embedded dimensions d < 8. Our results are inconsistent with earlier studies of Baker et al. (1990, https://doi.org/10.1029/GL017i001p00041), Pavlos et al. (1992), D. Roberts et al. (1991, https://doi.org/10.1029/91GL00021), D. A. Roberts (1991, https://doi.org/10.1029/91JA01088), and Vassiliadis et al. (1990, https://doi.org/10.1029/GL017i011p01841, 1991, https://doi.org/10.1029/91GL01378) indicating that auroral geomagnetic indices could be reduced to low-dimensional systems with chaotic dynamics.