Improving Models to Better Represent the Complex Structure of Coronal Mass Ejections

该奖项是为了支持对日冕物质抛射（CME）结构的研究。cme是太阳或风暴的喷发，向太阳系释放数十亿吨物质和强电磁场。当它们指向地球时，通常需要大约三天才能到达，然而，非常强大的风暴可以在短短18小时内到达。这使得准备卫星和电网中断的准备时间非常短。日冕物质抛射在穿越太阳系的过程中会改变其特征。因此，了解日冕物质抛射的结构以及这些变化是如何发生的，对于了解日冕物质抛射何时到达地球以及它将如何影响地球磁场和我们的基本资产非常重要。该项目支持早期职业科学家首次担任PI。尽管在过去的几十年里，日冕物质抛射的内部结构一直是众多研究的主要焦点，但它们的结构仍然存在很大的模糊性。尽管在近地环境中对日冕物质抛射进行了数十年的原位测量，但现有技术、规范和模型的缺陷限制了我们对这些重要而复杂的结构的了解。目前的缺乏理解可以概括为两点：(1)测量本身的局限性，更重要的是，(2)由于分析这些测量所做的假设的局限性。大多数进行的研究仍然假设一个圆柱对称线性无力（伦德奎斯特）的解决方案。与此同时，对日冕物质抛射在太阳上的婴儿期和后来的传播过程进行的新的远程观测，揭示了这些结构的复杂程度。该项目将把观测和模拟日冕物质抛射的更多物理特征纳入拟合和重建代码，包括它们随时间的扩展和演变（老化），航天器轨道的影响，以及比组织良好的圆形扭曲磁通绳更复杂的磁场结构的存在。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 award is to support the investigation of Coronal Mass Ejection (CME) structures. CMEs are eruptions from the sun or storms which release billions of tons of material and strong electromagnetic fields into the solar system. When directed at Earth, they typically take about three days to arrive, however, very powerful storms can arrive in as few as 18 hours. This gives very little lead time in which to prepare for disruptions to satellites and to power grids. CMEs change characteristics as they move through the solar system. Therefore, understanding the structure and how these changes occur is very important for understanding when a CME will arrive at Earth and how it will impact Earth’s magnetic field and our essential assets. This project supports an early career scientist for their first time as PI.Even though the internal structure of CMEs has been the main focus of numerous studies over the past several decades, there are still large ambiguities regarding their structure. In spite of having decades of in situ measurements of CMEs in the near-Earth environment, shortcomings of the existing techniques, codes and models limit what we can learn about these important and complex structures. The current lack of understanding can be summarized into two main points: (1) limitations of the measurements themselves, and more importantly, (2) limitations due to the assumptions made to analyze these measurements. The majority of performed studies still assume a cylindrical symmetric Linear force-free (Lundquist) solution. At the same time, new remote observations of CMEs in their infancy at the Sun and later on, as they propagate, reveal how complex these structures are. This project will incorporate more of the physical features of observed and simulated CMEs into fitting and reconstruction codes, including their expansion and evolution over time (aging), the effect of spacecraft trajectory, and the existence of more complex magnetic field structures than just a well-organized circular twisted magnetic flux rope.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.