Near‐Earth heliospheric magnetic field intensity since 1750: 2. Cosmogenic radionuclide reconstructions
Near‐Earth heliospheric magnetic field intensity since 1750: 2. Cosmogenic radionuclide reconstructions
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1750年以来的近地日光层磁场强度：2.宇宙成因放射性核素重建
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发表时间：
2016
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通讯作者：
Y.
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作者：
Mathew J. Owens;E. Cliver;K. McCracken;J. Beer;L. Barnard;Mike Lockwood;A. Rouillard;Dário Passos;Pete Riley;Ilya Usoskin;Y.
这是 1750 年以来近地日光层磁场强度 B 研究的第二部分。第 1 部分根据 1750 年至 2013 年期间的地磁和太阳黑子数据对 B 进行了综合估计。基于太阳黑子的重建可以追溯到 1610 年，但古宇宙射线 (PCR) 记录是唯一能够提供千年时间尺度太阳活动记录的数据集。将冰芯中测得的 10Be 浓度转换为 B 的过程比地磁和太阳黑子数据更为复杂，并且源自宇宙成因核素的 B 的不确定性（任何年份约为 20%）要大得多。在这种不确定性水平内，我们发现基于 PCR 的 B 与基于地磁和太阳黑子数的序列之间总体上合理。通过删除归因于高能太阳质子事件的基于 PCR 的 B 的低值，增强了这一一致性。我们的分析中仍包括其他不一致的间隔，其原因尚未明确。以太阳黑子最小值为中心的 3 年平均值的比较得出了三个估计值之间的合理一致性，从而提供了一种研究过去日光层磁场的长期变化的方法，即使没有方法从记录中删除太阳质子事件。
This is Part 2 of a study of the near‐Earth heliospheric magnetic field strength, B, since 1750. Part 1 produced composite estimates of B from geomagnetic and sunspot data over the period 1750–2013. Sunspot‐based reconstructions can be extended back to 1610, but the paleocosmic ray (PCR) record is the only data set capable of providing a record of solar activity on millennial timescales. The process for converting 10Be concentrations measured in ice cores to B is more complex than with geomagnetic and sunspot data, and the uncertainties in B derived from cosmogenic nuclides (~20% for any individual year) are much larger. Within this level of uncertainty, we find reasonable overall agreement between PCR‐based B and the geomagnetic‐ and sunspot number‐based series. This agreement was enhanced by excising low values in PCR‐based B attributed to high‐energy solar proton events. Other discordant intervals, with as yet unspecified causes remain included in our analysis. Comparison of 3 year averages centered on sunspot minimum yields reasonable agreement between the three estimates, providing a means to investigate the long‐term changes in the heliospheric magnetic field into the past even without a means to remove solar proton events from the records.