Abstract Long-term variations in annual frequencies of occurrence of magnetic storms with sudden and gradual commencements were studied on the base of the data from IZMIRAN and Slutsk (Pavlovsk) magnetic observatories for the period 1878–2015. It was found that occurrences of strong and moderate magnetic storms with gradual commencements are characterized by a pronounced variability on the multidecadal time scale. Their wavelet spectra reveal strong periodicities of ~36 years (close to the climatic Bruckner cycle), as well as less pronounced ~60-year and ~90-year ones throughout the entire time interval under study. The occurrences of strong, moderate and weak magnetic storms with sudden commencements are characterized by dominating ~11-year periodicities, whereas long-term variations are substantially weaker. The obtained results provide evidence for a different temporal evolution of local and global solar magnetic fields responsible for solar agents (CMEs and high-speed solar wind streams from coronal holes) contributing to the development of these types of magnetic storms. The obtained results allow suggesting a possible contribution of solar/geomagnetic activity to the formation of climatic oscillations on the multidecadal time scale.

中文翻译：

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突然和逐渐开始的磁暴发生频率的长期变化

摘要 以伊兹米兰和斯卢茨克（巴甫洛夫斯克）磁观测站1878-2015年磁观测资料为基础，研究了具有突然和逐渐开始的磁暴年发生频率的长期变化。发现逐渐开始的强和中度磁暴的发生的特征是在几十年的时间尺度上具有明显的可变性。他们的小波谱显示出~36 年的强周期性（接近气候布鲁克纳周期），以及在整个研究时间间隔内不太明显的~60 年和~90 年的周期性。突然开始的强、中、弱磁暴的发生以占主导地位的~11年周期为特征，而长期变化则明显较弱。获得的结果为导致这些类型磁暴发展的太阳代理（CME 和来自日冕孔的高速太阳风流）负责的局部和全球太阳磁场的不同时间演变提供了证据。获得的结果表明太阳/地磁活动可能对数十年时间尺度上气候振荡的形成做出贡献。