Seven different models are applied to the same problem of simulating the Sun’s coronal magnetic field during the solar eclipse on 2015 March 20. All of the models are non-potential, allowing for free magnetic energy, but the associated electric currents are developed in significantly different ways. This is not a direct comparison of the coronal modelling techniques, in that the different models also use different photospheric boundary conditions, reflecting the range of approaches currently used in the community. Despite the significant differences, the results show broad agreement in the overall magnetic topology. Among those models with significant volume currents in much of the corona, there is general agreement that the ratio of total to potential magnetic energy should be approximately 1.4. However, there are significant differences in the electric current distributions; while static extrapolations are best able to reproduce active regions, they are unable to recover sheared magnetic fields in filament channels using currently available vector magnetogram data. By contrast, time-evolving simulations can recover the filament channel fields at the expense of not matching the observed vector magnetic fields within active regions. We suggest that, at present, the best approach may be a hybrid model using static extrapolations but with additional energization informed by simplified evolution models. This is demonstrated by one of the models.

中文翻译：

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2015 年 3 月日食期间日冕的全球非势磁模型

七个不同的模型被应用于模拟 2015 年 3 月 20 日日食期间太阳日冕磁场的同一问题。所有模型都是非势能的，允许自由磁能，但相关电流的发展有显着不同方法。这不是日冕建模技术的直接比较，因为不同的模型也使用不同的光球边界条件，反映了社区当前使用的方法的范围。尽管存在显着差异，但结果显示总体磁拓扑具有广泛的一致性。在大部分日冕中具有显着体积电流的模型中，普遍同意总磁能与势磁能的比率应约为 1.4。然而，电流分布有显着差异；虽然静态外推最能重现活动区域，但它们无法使用当前可用的矢量磁图数据恢复灯丝通道中的剪切磁场。相比之下，时间演化模拟可以恢复灯丝通道场，但代价是不匹配活动区域内观察到的矢量磁场。我们建议，目前最好的方法可能是使用静态外推的混合模型，但通过简化的进化模型提供额外的能量。模型之一证明了这一点。他们无法使用当前可用的矢量磁图数据恢复灯丝通道中的剪切磁场。相比之下，时间演化模拟可以恢复灯丝通道场，但代价是不匹配活动区域内观察到的矢量磁场。我们建议，目前最好的方法可能是使用静态外推的混合模型，但通过简化的进化模型提供额外的能量。模型之一证明了这一点。他们无法使用当前可用的矢量磁图数据恢复灯丝通道中的剪切磁场。相比之下，时间演化模拟可以恢复灯丝通道场，但代价是不匹配活动区域内观察到的矢量磁场。我们建议，目前最好的方法可能是使用静态外推的混合模型，但通过简化的进化模型提供额外的能量。模型之一证明了这一点。