In this study, we used the flare index (FI) data taken from Kandilli Observatory for the period of 2009–2020. The data sets are analyzed in three categories as Northern Hemisphere, Southern Hemisphere, and total FI data sets. Total FI data set is obtained from the sum of Northern and Southern Hemispheric values. In this study, the periodic variations of abovementioned three categories FI data sets were investigated by using the MTM and Morlet wavelet analysis methods. The wavelet coherence (XWT) and cross wavelet (WTC) analysis methods were also performed between these data sets. As a result of our analysis, the following results were found: (1) long- and short-term periodicities ( day and periodicities smaller than 62 days) exist in all data sets without any exception at least with confidence level; (2) all periodic variations were detected maximum during the solar cycle, while during the minima, no meaningful period is detected; (3) some periodicities have data preference that about 150 days Rieger period appears only in the whole data set and 682-, 204-, and 76.6-day periods appear only in the Northern Hemisphere data sets; (4) During the Solar Cycle 24, more flare activity is seen at the Southern Hemisphere, so the whole disk data periodicities are dominated by this hemisphere; (5) in general, there is a phase mixing between Northern and Southern Hemisphere FI data, except about 1024-day periodicity, and the best phase coherency is obtained between the Southern Hemisphere and total flare index data sets; (6) in case of the Northern and Southern Hemisphere FI data sets, there is no significant correlation between two continuous wavelet transforms, but the strongest correlation is obtained for the total FI and Southern Hemisphere data sets.

中文翻译：

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最后一个太阳周期（周期 24）的太阳耀斑指数的周期性变化

在这项研究中，我们使用了从 Kandilli 天文台获取的 2009-2020 年期间的耀斑指数 (FI) 数据。数据集按北半球、南半球和总 FI 数据集三类进行分析。总 FI 数据集是从北半球和南半球值的总和中获得的。本研究利用MTM和Morlet小波分析方法研究了上述三类FI数据集的周期性变化。在这些数据集之间还进行了小波相干 (XWT) 和交叉小波 (WTC) 分析方法。作为我们分析的结果，发现了以下结果：（1）长期和短期的周期性（天和周期小于 62 天）存在于所有数据集中，至少有置信水平；(2) 在太阳活动周期内检测到所有周期性变化最大，而在最小值期间，没有检测到有意义的周期；(3) 部分周期有数据偏好，150天左右的Rieger周期只出现在整个数据集中，682天、204天、76.6天的周期只出现在北半球数据集中；(4) 24日太阳活动周期期间，南半球出现较多的耀斑活动，因此整个盘面数据周期以该半球为主；(5) 总体而言，北半球和南半球 FI 数据之间存在相位混合，除了大约 1024 天的周期性，并且在南半球和总耀斑指数数据集之间获得了最好的相位相干性；(6) 在北半球和南半球 FI 数据集的情况下，