What can the annual 10 Be solar activity reconstructions tell us about historic space weather?
What can the annual 10 Be solar activity reconstructions tell us about historic space weather?
复制标题
年度 10 Be 太阳活动重建可以告诉我们有关历史空间天气的哪些信息？
DOI：
10.1051/swsc/2018014
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发表时间：
2018
影响因子：
3.3
通讯作者：
Barnard L
中科院分区：
文献类型：
--
作者：
Barnard L
背景：宇宙成因的同位素为过去的太阳磁活动提供了有用的估计，以合理的不确定性约束了过去的空间气候。人们对过去的太空天气状况知之甚少。MB15在分析10Be方面的最新进展表明，太阳高能粒子(SEP)通量对10Be的年分辨率有很大影响。这带来了一个问题，也提供了一个机会，因为准确量化过去的太阳磁活动需要确定和隔离SEP效应，而这样做可能会提供过去SEP通量的有价值的记录。目的：我们比较日球层磁场(HMF)的MB15重建，与根据太阳黑子记录和地磁变化得出的HMF的两个独立估计。我们的目标是量化HMF重建之间的差异，并推测这些差异的来源。我们检验重建之间的差异是否取决于已知的重大空间天气事件。方法：我们分析HMF重建之间的差异的分布。我们考虑了这种差异是如何随着太阳周相的变化而变化的，并使用Kolmogorov-Smirnov检验，比较了在是否发生大型空间天气事件这两种情况下的分布。结果：我们发现MB15重建的震级通常比太阳黑子和地磁HMF重建的震级略小。这种偏差随着太阳周期阶段的变化而变化，在太阳周期的衰退期最大。我们发现，MB15‘S剔除了地面高度极大增强的年份，改进了10Be HMF估计与太阳黑子和地磁重建的一致性。我们没有发现GLES总体上影响MB15重建的统计证据，但这种分析受到样本太少的限制。我们确实发现了证据表明，在地磁风暴强烈的年份，MB15重建看起来在统计上是不同的。
Context: Cosmogenic isotopes provide useful estimates of past solar magnetic activity, constraining past space climate with reasonable uncertainty. Much less is known about past space weather conditions. Recent advances in the analysis of10Be by (MB15) suggest that annually resolved10Be can be significantly affected by solar energetic particle (SEP) fluxes. This poses a problem, and presents an opportunity, as the accurate quantification of past solar magnetic activity requires the SEP effects to be determined and isolated, whilst doing so might provide a valuable record of past SEP fluxes.Aims: We compare the MB15 reconstruction of the heliospheric magnetic field (HMF), with two independent estimates of the HMF derived from sunspot records and geomagnetic variability. We aim to quantify the differences between the HMF reconstructions, and speculate on the origin of these differences. We test whether the differences between the reconstructions appear to depend on known significant space weather events.Methods: We analyse the distributions of the differences between the HMF reconstructions. We consider how the differences vary as a function of solar cycle phase, and, using a Kolmogorov-Smirnov test, we compare the distributions under the two conditions of whether or not large space weather events were known to have occurred.Results: We find that the MB15 reconstructions are generally marginally smaller in magnitude than the sunspot and geomagnetic HMF reconstructions. This bias varies as a function of solar cycle phase, and is largest in the declining phase of the solar cycle. We find that MB15's excision of the years with very large ground level enhancement (GLE) improves the agreement of the10Be HMF estimate with the sunspot and geomagnetic reconstructions. We find no statistical evidence that GLEs, in general, affect the MB15 reconstruction, but this analysis is limited by having too few samples. We do find evidence that the MB15 reconstructions appear statistically different in years with great geomagnetic storms.