Space and Atmospheric Electricity Group, Department of Meteorology, University of Reading, Earley Gate, PO Box 243, Reading RG6 6BB, UK.
Predictive Science Inc., 9990 Mesa Rim Rd, Suite 170, San Diego, CA 92121, USA.
Sci Rep. 2017 Jan 31;7:41548. doi: 10.1038/srep41548.
The most recent "grand minimum" of solar activity, the Maunder minimum (MM, 1650-1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth's magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima.
最近一次太阳活动的“大极小期”，即蒙德极小期（Maunder minimum，MM，1650-1710 年），对于理解太阳发电机以及洞察未来可能的日球层条件都非常重要。在这里，我们使用了近 30 年的数据约束磁流体力学模型对太阳日冕的输出进行了校准，该模型仅基于太阳黑子观测来进行日球层重建。利用这些经验关系，我们首次对过去 400 年全球太阳风变化进行了定量估计。与现代相比，MM 时期近地日球层磁场强度和太阳风速度降低了 2 倍，太阳风马赫数最高增加了 4 倍。因此，太阳风能量输入到地球磁层减少，导致更类似于木星的系统，这与当时极光报告稀少的情况一致。在 MM 条件下，全球日球层更小且更对称，这对日球层宇宙成因放射性核素数据的解释以及大极小期期间的总太阳辐照度估计有影响。
