The midrange periodicities of solar H$\alpha $ flare index during Solar Cycles 21–24
The midrange periodicities of solar H$\alpha $ flare index during Solar Cycles 21–24
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DOI：
10.1007/s10509-021-03954-2
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发表时间：
2021-07
影响因子：
1.9
通讯作者：
C. Li;Y. Fei;X. Tian;J. An
中科院分区：
文献类型：
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作者：
C. Li;Y. Fei;X. Tian;J. An
太阳磁活动指数在大气各层中的时空变化对于理解和揭示太阳磁场的动力学过程具有重要意义。本文用Lomb-Scarge周期图技术和MonteCarlo显著性检验方法研究了第21-24太阳周耀斑指数的中期周期（50-500天）。主要结果如下：（1）在强振幅太阳活动周中，中等周期数较少（21和22）而弱振幅太阳周期（23和24）显示了更多的中程周期;（2）120-180天的Rieger型周期（中心周期为154天）及其二次和三次谐波（大约52和73天）存在于所有太阳周期中;（3）在某些太阳活动周中，还发现了其它一些中程周期，包括27天自转周期、10周自转周期和年变信号。这些中程周期性，揭示了时间-频率分析技术，可能的解释的基础上的磁通量的周期性出现。
The temporal and spatial variations of solar magnetic activity indices in the various atmospheric layers are important for understanding and revealing the dynamic processes of magnetic field of the Sun. In this paper, the midrange periodicities (located at 50-500 days) of the solar Hflare index during Solar Cycles 21–24 were studied by the Lomb–Scarge periodogram technique and the Monte Carlo significance test. The main results are as follows: (1) a lesser number of midrange periodicities is found in the strong-amplitude solar cycles (21 and 22) while the weak-amplitude solar cycles (23 and 24) show a greater number of midrange periodicities; (2) the Rieger-type periodicity in the range 120–180 days (the central periodicity is 154 days) and its two and three subharmonics (around 52 and 73 days) exist in all solar cycles; (3) some other midrange periodicities, including the 27-day rotation period, the ten-rotation periodicity, and the annual-variation signal, are also found in certain solar cycles. Possible explanations of these midrange periodicities, revealed by the time–frequency analysis technique, are presented on the basis of the periodic emergences of magnetic flux.