Nonlinear time series analysis of ionospheric electric current disturbance associated with geomagnetic storm

The wavelet power spectrum and nonlinear dynamics time series techniques were used to examine the ionospheric electric current disturbance (Diono) during the geomagnetic storms of 9-11 November 2004 and 14-16 May 2005. These storms were characterized by high solar wind speed from coronal mass ejections (CMEs). The time series of the solar wind parameters (interplanetary magnetic field, IMF Bz and solar wind speed, Vx) and geomagnetic indices (Symmetric disturbance field, SYM-H, eastward electrojet, AU and westward electrojet AL), were used to monitor solar wind conditions and the geomagnetic perturbation, respectively. The horizontal component of the geomagnetic field obtained from six ground-based magnetometer stations was also analyzed. The high latitudes stations (ESK, NUR, LER and SOD) show higher energy wavelet coefficient of Diono with high frequencies, due to the existence of ionospheric currents at high latitudes during geomagnetic storm. The mid and low latitude stations (HER and AAE) display low energy wavelet coefficient with low frequency. The low latitude geomagnetic stations display high values of Lyapunov exponent (LE) during 9-11 November 2004 and 14-16 May 2005 of the geomagnetic storm. The low values of Lyapunov exponent might be as result of the internal dynamics restructuring during geomagnetic storm. The electrodynamics of the magnetosphere-ionosphere due to solar wind influenced the chaotic signature of Diono. The solar wind is a stochastic driver which contributes in the generation of geomagnetic disturbance in the Earth's magnetosphere due to CMEs that generates the geomagnetic storms. (c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.

Automated summary

In this study, the wavelet power spectrum and nonlinear dynamics time series techniques were employed to investigate the ionospheric electric current disturbance (Diono) during the geomagnetic storms of 9-11 November 2004 and 14-16 May 2005. The results revealed that high latitudes stations exhibited higher energy wavelet coefficients of Diono at high frequencies, indicating the presence of ionospheric currents during geomagnetic storms. On the other hand, mid and low latitude stations displayed lower energy wavelet coefficients at low frequencies. Additionally, the low latitude geomagnetic stations showed higher values of Lyapunov exponent (LE) during the geomagnetic storms.