Processing Solar Activity data by Spectral and Recurrence Analysis methods

Author: Luka Burdiladze
Keywords: solar activity, Sunspots, Wolf number, Fourier analysis, Wavelet analysis, Hilbert-Huang transform, Recurrence Quantification Analysis
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In this bachelor's thesis, we processed one of the indices of solar activity, Wolf Number(Relative Sunspot Number), using the following data analysis methods: Fourier Analysis, Wavelet Analysis, Hilbert-Huang Transform and Recurrence Quantification Analysis (RQA). Spectral analysis methods have found the well-known solar activity period of 11 years and longer periods as well. Compared to the Fourier and Wavelet Analysis methods, the Hilbert-Huang Transform found quantitatively more and shorter periods. We investigated the dynamics of solar activity with several RQA measures. During solar activity, phase transitions have been observed that coincide with the minimum of activity. Analyzing the 21st century data, a new minimum has been observed, which will not be similar to the Maunder minimum. Wolf number data from the SILSO world database center was processed with MATLAB and Python mathematical packages.