Collaborative Research: Reconciliation Between In-situ and Remote Sensing Analyses

太阳上的喷发将带电的气体云和强磁场称为日冕物质抛射，射入太空。其中一些云是无害的，而另一些云则可以穿透并破坏地球周围的空间环境，这一现象被称为地磁暴。了解产生风暴的太阳扰动非常重要，因为恶劣的太空天气会损坏围绕地球运行的卫星，危及宇航员，甚至扰乱地球表面的电网--S。太阳附近观测到的日冕物质抛射的特征并不是一成不变的，而是在其到达地球的途中通过背景日光层不断演变，甚至与其他太阳扰动和行星际空间的大尺度磁场和等离子体结构相互作用，这一事实阻碍了对强磁暴的准确预测。由于日冕物质抛射在传播到地球的过程中结构发生了变化，因此发生了重大风暴。为了了解并最终更好地预测日冕物质抛射对地球--S空间环境的影响，该项目将遥感和现场观测相结合，并与大规模模拟相比较，详细研究了日冕物质抛射通过日光层时特征的变化，以及导致这些变化的物理机制。作为该项目的一个成果，将向更广泛的科学界在线提供一个大型的事件和相关观测数据库。成果将在科学出版物中传播，并通过在研讨会和会议上的陈述来传播。该项目支持培训一名博士后研究员，他将在新汉普郡大学工作，但将与NASA戈达德太空飞行中心和海军研究实验室的合作研究人员一起工作。这位博士后研究人员的支持也有助于扩大STEM领域中代表性不足的群体的参与。此外，该项目将通过参与美国宇航局戈达德太空飞行中心的高影响力研究，每年在夏季几个月对一名本科生进行培训。该项目利用目前使用遥感和现场仪器观测内日光层的一套卫星，回答有关瞬变太阳扰动(特别是日冕物质抛射)及其在传播过程中如何变化的基本问题。这些卫星包括Wind、ACE、Messenger、STEREO、SOHO和SDO。遥感仪器在日冕物质抛射离开太阳时观察到它，而原位仪器则在它向外掠过日光层时测量它的内部结构。日冕物质抛射的特征是使用先前测试的模型从每种类型的测量中推断出来的。一个关键要求是将这两种非常不同类型的数据结合在一起的一致和可靠的方法，这将应用于大约100个事件。作为制定方法的一部分，将调和从各种数据来源推断的日冕物质抛射特征的差异。当与大规模磁流体力学模拟相结合时，将对潜在的物理机制进行研究，尽管仅限于有限数量的此类情况。要调查的问题包括：查明不清楚的太阳源、未确定的膨胀率、传播中存在经度/纬度偏转的证据、日冕物质抛射因与太阳风结构或其他瞬变事件的碰撞而发生变化的证据，以及磁通量绳自转的查明。

Eruptions on the Sun eject clouds of electrically charged gas and strong magnetic fields called coronal mass ejections into space. Some of these clouds are harmless while others can penetrate into and disrupt the space environment around Earth in space weather events called geomagnetic storms. Understanding the solar disturbances that produce storms is important because severe space weather can damage satellites orbiting around Earth, endanger astronauts, and even disrupt power grids on the Earth?s surface. Accurate forecasting of strong magnetic storms is hindered by the fact that the features of a coronal mass ejection observed near the Sun do not remain constant but continually evolve as it moves through the background heliosphere on its way to Earth even interacting with other solar disturbances and with large scale magnetic fields and plasma structures in interplanetary space. Major storms have occurred due to changes in the structure of the coronal mass ejection during its propagation to Earth. In an effort to understand and eventually better predict the impacts of coronal mass ejections on the Earth?s space environment, this project takes a detailed look at the changes in the characteristics of coronal mass ejections as they move through the heliosphere, and at the physical mechanisms responsible for those changes, by combining remote-sensing and in-situ observations and comparing to large scale simulations. As an outcome of the project, a large database of events and associated observations will be made available online for the broader scientific community. Results will be disseminated in scientific publications, and through presentations at workshops and conferences. The project supports the training of a post doctoral researcher who will be based at the University of New Hampshire but will spend time working with co-investigators at both NASA Goddard Space Flight Center and the Naval Research Laboratory. Support of this postdoctoral researcher also serves to broaden the participation of an underrepresented group in a STEM field. In addition, the project will contribute to the training of an undergraduate student each year during the summer months through involvement in high-impact research at NASA Goddard Space Flight Center.This project takes advantage of a suite of satellites currently observing the inner heliosphere with remote-sensing and in-situ instruments to answer fundamental questions about transient solar disturbances (in particular, coronal mass ejections) and how they change during propagation. These satellites include Wind, ACE, Messenger, STEREO, SOHO, and SDO. Remote-sensing instruments view the coronal mass ejection as it lifts off the Sun while in-situ instruments measure its internal structure as it sweeps by on its way outward through the heliosphere. The characteristics of coronal mass ejections are inferred from each type of measurement using previously tested models. A key requirement is a consistent and robust methodology for combining these two very different types of data, which will be applied to some 100 events. As part of the development of the methodology, the discrepancies in the inferred characteristics of the coronal mass ejection from the various data sources will be reconciled. When combined with large-scale magnetohydrodynamic simulations a study of the underlying physical mechanisms will be made albeit restricted to a limited number of these cases. Issues to be investigated include: the identification of unclear solar sources, undefined expansion rates, evidence of longitudinal/latitudinal deflections in the propagation, evidence for modifications of the coronal mass ejection due to collisions with solar wind structures or other transient events, and identification of magnetic flux-rope rotations.