Galactic cosmic rays as observed by the Hermanus and Jungfraujoch Neutron Monitors between 1960 and 2018 have been analysed using various spectral analysis techniques. Daily mean neutron monitor measurements are used to identify how several harmonics of the roughly 27-day synodic rotation period change during each of these years. Spectral analysis using Lomb-Scargle and Morlet wavelet techniques of Hermanus and Jungfraujoch data revealed in particular that the fourth harmonic (∼7-day) of the solar rotation period is exceptionally strong during the minima of solar cycles when A 0 (solar dipole pointing north). The power spectrum results obtained in this investigation showed that galactic cosmic rays at both Hermanus and Jungfraujoch exhibit peculiar short-term periodicity behaviour as a result of solar polarity dependent magnetic drifts during negative minima.

中文翻译：

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不同太阳磁极间隔期间银河宇宙线27天周期的四次谐波行为

赫曼努斯和少女峰中子监测器在 1960 年至 2018 年间观测到的银河宇宙射线已使用各种光谱分析技术进行了分析。每日平均中子监测测量用于确定这些年中每年大约 27 天的会合旋转周期的几个谐波如何变化。使用 Hermanus 和 Jungfraujoch 数据的 Lomb-Scargle 和 Morlet 小波技术进行的光谱分析特别表明，当 A 0（太阳偶极子指向北）。