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WAVELET ANALYSIS OF THE GEOMAGNETIC STORM OF JANUARY 19-21, 2026

Asimopolos Laurentiu, Adrian-Aristide Asimopolos, Natalia-Silvia Asimopolos

Abstract

The geomagnetic field varies in time and space, being a signal composed of periodic and non-periodic elements and is monitored in a triaxial system at observatories around the world. Based on data from INTERMAGNET observatories, we analyze the strongest storm of 2026, which occurred during January 19-21. The methodology used is spectral evaluation (Fourier, wavelet, signal decomposition into approximations and details with various functions on different levels, etc.). The wavelet technique allowed us to analyze the local components of the magnetic field through variable frequency windows and different functions. Windows with longer time intervals allowed us to extract low-frequency information, the average times of the windows led us to extract medium-frequency information, and very narrow windows highlight high frequencies or details of the analyzed signals. Geomagnetic disturbances, substorms, and storms are non-periodic oscillations caused by Sun ejections (CMEs) and the impact of the solar wind on the Earth's magnetosphere. Wavelet coherence is applicable to the analysis of non-stationary signals and uses the analytical Morlet wavelet, which can detect events such as geomagnetic field anomalies, change points, and transitions. The arrows in the coherence plot indicate the phase relationship between the two signals at each time and frequency (or period) point. The phase angle of the cross-spectrum is the same as the phase difference between the signals. From the data analyzed from geomagnetic observatories for the triaxial components and the total field, very good wavelet correlation and coherence were found during the analyzed geomagnetic storm. In addition, the correlations of geomagnetic observatory data with astrophysical data from specialized sites were highlighted.

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