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

这个为期两年的急切项目旨在改进目前的日冕物质抛射(CME)模型，该模型假定一个简单的、扭曲的绳状结构的简化结构。当前模型中假定的结构不足以捕捉其演化的全部复杂性。这个模型将包括一个更复杂的形式的索状结构的轴线。这一点很重要，因为日冕物质抛射的实际观测结果与简单的模型并不相符。这样的模型有可能显著改进对CME撞击地球时磁场方向的预测，这是空间天气预报的关键问题。具体地说，这个项目是开发一个数学模型，将扭动纳入当前扭曲的磁通量绳模型中。这将被用来研究螺旋度在CME中是如何以不同的形式表现出来的，它是如何从一种形式转变为另一种形式(例如，从扭曲到扭曲)，以及如何根据总螺旋度的守恒和CME中螺旋度主要形式的变化来理解与头盔流光重新连接的机制。这一新模式不仅将影响对日冕物质抛射就地测量的分析，而且还将改变整个地球航天界处理日冕物质抛射启动问题以及日冕物质抛射引起的风暴期间的太阳风-磁层耦合的方式。这还将使人们深入了解日冕物质系统在传播时的全球和地方结构。该模型将用于开发重建代码，并使用真实的CME观测(例如，由DKIST)和现场测量进行验证。该奖项反映了NSF的法定使命，并已通过使用基金会的智力优势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.