Temporal and Periodic Variation of the MCMESI for the Last Two Solar Cycles; Comparison with the Number of Different Class X-ray Solar Flares

• Published in: Solar physics Vol. 295; no. 11
• Main Authors: Kilcik, Ali, Chowdhury, Partha, Sarp, Volkan, Yurchyshyn, Vasyl, Donmez, Burcin, Rozelot, Jean-Pierre, Ozguc, Atila
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.11.2020; Springer Nature B.V
• Subjects: Astrophysics and Astroparticles; Atmospheric Sciences; Correlation analysis; Cross correlation; Datasets; Morlet wavelet; Periodic variations; Physics; Physics and Astronomy; Solar cycle; Solar flares; Solar physics; Solar x-rays; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Wavelet analysis; Wavelet transforms; Sun: flares; Sun: oscillations; Methods: data analysis; Sun: activity; Sun: coronal mass ejections (CMEs)
• ISSN: 0038-0938; 1573-093X
• DOI: 10.1007/s11207-020-01711-2

In this study we compared the temporal and periodic variations of the Maximum CME Speed Index (MCMESI) and the the number of different class (C, M, and X) solar X-ray flares for the last two solar cycles (Solar Cycles 23 and 24). To obtain the correlation between the MCMESI and solar flare numbers the cross-correlation analysis was applied to monthly data sets. Also to investigate the periodic behavior of all data sets the Multi Taper Method (MTM) and the Morlet wavelet analysis method were performed with daily data from 2009 to 2018. To evaluate our wavelet analysis Cross Wavelet Transform (XWT) and Wavelet Transform Coherence (WTC) methods were performed. Causal relationship between data sets were further examined by Convergence Cross Mapping (CCM) method. As results of our analysis we found the following: i) The C class X-ray flare numbers increased about 16% during the Solar Cycle 24 compared to Cycle 23, while all other data sets decreased; the MCMESI decreased about 16% and the number of M and X class flares decreased about 32%. ii) All the X-ray solar flare classes show remarkable positive correlation with the MCMESI. While the correlation between the MCMESI and C class flares comes from the general solar cycle trend, it mainly results from the fluctuations in the data in case of the X class flares. iii) In general, all class flare numbers and the MCMESI show similar periodic behavior. iv) The 546-day periodicity detected in the MCMESI may not be of solar origin or at least the solar flares are not the source of this periodicity. v) C and M class solar flares have a stronger causative effect on the MCMESI compared to X class solar flares. However, the only bidirectional causal relationship is obtained between the MCMESI and C class flare numbers.