EAGER: Developing an Ab initio Model of Coronal Mass Ejections (CMEs) Incorporating All Forms of Helicity

这个为期两年的EAGER项目旨在改进当前的日冕物质抛射（CME）模型，该模型假设了一个简单的扭曲绳状结构的简化结构。当前模型中假设的结构不足以捕捉它们进化的全部复杂性。这个模型将包含一个更复杂的形式的轴的这种绳状结构。这一点很重要，因为对日冕物质抛射的实际观测与简单模型并不相符。这样的模型有可能显著改善CME撞击地球时磁场方向的预测，这是空间天气预报的一个关键问题。具体来说，本项目是建立一个数学模型，将扭曲纳入现有的扭曲通量绳模型。这将用于研究螺旋度如何在日冕抛射中以不同的形式表现出来，它如何从一种形式转变为另一种形式（例如，从扭曲到扭动），以及如何根据总螺旋度的守恒和日冕抛射中螺旋度的主要形式的变化来理解与头盔流光的重连等机制。这种新模型不仅会影响日冕物质抛射的原位测量分析，而且会改变整个地球空间界对日冕物质抛射起始问题以及日冕物质抛射驱动风暴期间太阳风-磁层耦合的研究方法。这也将有助于我们了解日冕物质抛射传播过程中的全球和局部结构。该模型将用于开发重建代码，并使用实际CME观测（例如DKIST）和原位测量来验证它。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This two-year EAGER project seeks to improve on the current coronal mass ejection (CME) models which assume a simplified structure of a simple, twisted rope-like structure. The structure assumed in current models is insufficient for capturing the full complexity of their evolution. This model will incorporate a more complex form of the the axis of this rope-like structure. This is important because actual observations of CMEs do not match with the simple model. Such a model has the potential to lead to a significantly improved prediction of the magnetic field direction when the CME hits Earth, a key problem for space weather forecasting.Specifically, this project is to develop a mathematical model for incorporating writhe into the current twisted flux-rope models. This will be used to examine how helicity is manifested in different forms in a CME, how it transforms from one form to another (from twist to writhe, for example), and how mechanisms such as reconnection with helmet streamers may be understood in terms of conservation of total helicity and changes in the dominant form of helicity within a CME. Such a new model will not only influence the analysis of in situ measurements of CMEs, but also change the way the entire geospace community approaches the CME initiation problem as well as the solar wind-magnetosphere coupling during CME-driven storms. This will also provide an insight into both the global and local structure of CMEs as they propagate. This model will be used to develop a reconstruction code and validate it using real CME observations (for example by DKIST) and in situ measurements.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.