The Physics of Active Region Decay

利用磁流体动力学（MHD）模拟，提议小组将调查太阳大气中活跃区域的演变和衰减。这项工作将集中在活跃区衰变的物理学上，因为它对太阳周期发电机和确定太阳日冕中小规模和全局现象的详细磁结构都很重要。这一努力的动机是太阳活动区域（在光球层中被视为太阳黑子群，在全盘日冕图像中被视为x射线发射的明亮结）是太阳活动的最大和最重要的贡献者。太阳爆发现象（如太阳耀斑和日冕物质抛射，或cme）以及几乎所有观测到的到达地球的x射线和极紫外线辐射都与活跃区域磁场有关，但这些活跃区域的生命周期尚未得到很好的理解。首席研究人员（PI）指出，活动区域是空间天气的重要驱动因素，因此这项工作将对业务预测产生影响，特别是对太阳的全球磁性和大规模日冕物质抛射的预测。PI的团队将向社区提供他们的数字代码和数据集以进行测试和验证，他们希望他们的数字技术将有许多其他应用。提议小组的工具将在开源许可下提供，用于需要辐射MHD模型的广泛研究。

Using magnetohydrodynamic (MHD) simulations, the proposing team will investigate the evolution and decay of active regions in the solar atmosphere. This effort will focus on the physics of active region decay because of its importance to the solar cycle dynamo and for determining the detailed magnetic structure of both small-scale and global phenomena in the solar corona. This effort is motivated by the fact that solar active regions (seen as sunspot groups in the photosphere and bright knots of X-ray emission in full disk coronal images) are the largest and most important contributors to solar activity. Solar eruptive phenomena (such as solar flares and coronal mass ejections, or CMEs) and nearly all of the observed X-ray and extreme ultraviolet radiation that reaches the Earth are linked to active region magnetic fields, but the life cycle of these active regions is not yet well understood.The Principal Inverstigar (PI) notes that active regions are an important driver of space weather and that this work will therefore have an impact on operational forecasts, especially of the global magnetic properties of the Sun and large-scale CMEs. The PI's team will provide their numerical codes and datasets to the community for testing and validation, and they expect that their numerical techniques will have many additional applications. The proposing team's tools will be made available under an open source license for use in a wide range of studies in which radiative MHD models are needed.