Is Something Wrong With the Present Solar Maximum?
Is Something Wrong With the Present Solar Maximum?
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DOI：
10.1002/swe.20045
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发表时间：
2013-04
期刊：
影响因子：
--
通讯作者：
Y. Kamide;K. Kusano
中科院分区：
文献类型：
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作者：
Y. Kamide;K. Kusano
地磁风暴的发生会严重影响工程系统的运行。因此，确定当前太阳周期期间地磁暴的发生状态非常重要。根据标准太阳周期，太阳现在应该经历其周期的最大阶段。然而，目前的太阳似乎正处于一种独特而奇特的状态之中，因为太阳的行为在太阳周期的峰值阶段附近相当安静。因此，认识太阳的现状及其对地球环境的潜在影响是值得的。图 1 的顶部面板显示了每年的国际太阳黑子数量。很明显，目前太阳活动的黑子数量相对较低。事实上，这种低活动是在本周期开始之前就预测到的。例如，斯瓦尔加德等人。 [2005] 使用前一个太阳极小期的极地磁场作为下一个太阳极大期的磁场来预测第 24 周期将是 100 年来最弱的。依靠发电机理论，Jiang 等人。 [2007] 得出的结论是第 24 周期将很弱，而 Dikpati 和 Gilman [2006] 则预测第 24 周期将在峰值时最强。蓝色条显示每年大于 GOES X 射线等级 X1.0 的耀斑数量。还很明显的是，与之前的太阳极大期相比，第 24 周期 X 级耀斑的生产力相当低。底部面板显示了过去 3.5 个太阳周期内相应的地磁暴发生频率。地磁风暴已使用标准 Dst 指数来识别。所有风暴根据主阶段结束时的峰值Dst值（指定为Dstp）分为三类：
The occurrence of geomagnetic storms can seriously affect the operations of engineered systems. As such, it is important to determine the status of the occurrence of geomagnetic storms during the current solar cycle. According to the standard solar cycle, the Sun is now supposed to be going through the maximum phase of its cycle. The present Sun seems, however, to be in the middle of a unique and peculiar state in the sense that the Sun’s behavior is rather quiet near the peak phase of a solar cycle. It is therefore worthwhile to recognize the present state of the Sun and its potential impact on the Earth’s environment. The top panel of Figure 1 shows yearly international sunspot number. It is clear that the present solar activity in terms of sunspot number is relatively low. In fact, this low activity was predicted before the present cycle began. For example, Svalgaard et al. [2005] used the polar magnetic field at the preceding solar minimum for the next solar maximum to predict that cycle 24 would be the weakest in 100 years. Relying on a dynamo theory, Jiang et al. [2007] concluded that cycle 24 would be weak, in contrast to Dikpati and Gilman [2006] who predicted that cycle 24 would be the strongest at its peak. The blue bars show the yearly number of flares larger than GOES X-ray class X1.0. It is evident also that the productivity of X-class flares is fairly low in cycle 24, compared to the previous solar maxima. The bottom panel shows the corresponding occurrence frequency of geomagnetic storms over the past 3.5 solar cycles. Geomagnetic storms have been identified using the standard Dst index. All the storms have been classified into three categories according to the peak Dst value, designated as Dstp, at the end of the main phase: