Geomagnetic activity and the solar wind during the Maunder Minimum
Geomagnetic activity and the solar wind during the Maunder Minimum
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DOI：
10.1029/98gl00500
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发表时间：
1998-03
影响因子：
5.2
通讯作者：
E. Cliver;V. Boriakoff;K. Bounar
中科院分区：
文献类型：
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作者：
E. Cliver;V. Boriakoff;K. Bounar
我们利用太阳黑子数 (SSN) 11 年平均值与地磁 aa 指数之间的强相关性 (r = 0.96) 来推断，蒙德极小期 (1645-1715) 期间地磁活动的平均水平约为最近太阳周期观测到的水平的三分之一 (∼7 nT vs. ∼24 nT)。我们利用最近两个周期的周期平均 SSN 确定了太阳风速 (v) 和行星际磁场南向分量 (Bs) 的 11 年平均值的变化，并比较了同一时间间隔内 v²Bs 和 aa 的周期平均变化。然后，我们将这些观测到的太阳风变化外推到蒙德极小条件（平均 SSN 为 ∼ 2，平均 aa 值为 ∼ 7 nT），以推断出，平均而言，该时期的太阳风比现在（∼ 440 km s−1 和 ∼）稍慢一些（v = 340 ± 50 km s−1），并且行星际磁场更加平滑（Bs = 0.3±0.1 nT）。 1.2nT）。各种证据（包括 10Be 数据）表明，尽管蒙德极小期特征的太阳黑子实际上不存在，但 11 年的地磁（太阳风）周期在整个时期持续存在。
We used a strong (r = 0.96) correlation between 11‐year averages of sunspot number (SSN) and the geomagnetic aa index to infer that the mean level of geomagnetic activity during the Maunder Minimum (1645–1715) was approximately a third of that observed for recent solar cycles (∼7 nT vs. ∼24 nT). We determined the variation of 11‐year averages of solar wind speed (v) and the southward component of the interplanetary magnetic field (Bs) with cycle‐averaged SSN for the two most recent cycles and also compared cycle‐averaged variations of v²Bs and aa for the same interval. We then extrapolated these observed solar wind variations to Maunder Minimum conditions (mean SSN of ∼ 2 and mean aa value of ∼ 7 nT) to deduce that, on average, the solar wind during that period was somewhat slower (v = 340 ± 50 km s−1), and the interplanetary magnetic field much smoother (Bs = 0.3±0.1 nT), than at present (∼ 440 km s−1 and ∼ 1.2 nT). Various lines of evidence (including 10Be data) suggest that, despite the virtual absence of sunspots that characterized the Maunder Minimum, the 11‐year geomagnetic (solar wind) cycle persisted throughout this period.