太阳物理研究组知识库

日冕物质抛射（CME）是从太阳抛出的大尺度磁化等离子体团，携带大量磁通量和等离子体进入行星际空间。进入行星际空间的CME也被称为行星际CME （简称ICME），当它朝向地球运动并传播至地球附近时，会与磁层相互作用产生地磁暴和其他空间天气现象。现有观测结果提供的二维数据不能完整描述CME的真实磁场结构和等离子体分布。为了更好地预测ICME到达地球的时间以及对地球和周边环境可能产生的影响，需要了解CME的三维结构和速度的3个分量。介绍了根据现有的成像观测结果对CME进行三维重构的方法，包括基于日冕仪数据和日球成像数据的两类重构方法以及与CME成像重构关联度较高的CME驱动激波的三维重构方法。每种方法适合不同特点的CME事件，也有各自的局限性和需要满足的约束条件。我们对比了几种不同重构方法获得的结果，发现这些方法对CME的传播速度和传播角度的估算结果都比较接近，说明这些方法的可靠性高。最后对CME三维重构的热点问题和发展趋势进行了讨论。 

Coronal mass ejection (CME) is the large scale magnetized plasmoid ejected from the Sun, which brings huge amount of magnetic flux and plasma into interplanetary space. An earthward CME will interact with the magnetosphere of the Earth and invokes the substorm and the other phenomena of the space weather as it approaches to the Earth. The 2-dimansional data provided by the current observational techniques cannot describe the true magnetic structure and the plasma distribution of CMEs comprehensively. We need to look into the 3-dimensional structure and the associated three components of CME speeds in order to predict the time when an ICME reaches the Earth and the potential consequent impact on the Earth and the nearby environment. In this paper, 3D reconstruction methods of CME based on existing imaging observations are introduced, including two kinds of reconstruction methods based on coronagraph data and heliosphere imager data and CME-driven shock wave 3D reconstruction methods with high correlation with CME imaging reconstruction. Each method shows apparent advantages in dealing with specific events, but its weakness and necessary constrains to its applications exist as well. Results obtained via various methods are compared in this work, and we found that CME velocities and moving directions deduced from these methods are fairly close to one another, which shows high reliability of these methods. Finally, the hot topics related to the 3-dimanesional reconstruction of CME (ICME) and the relevant development in reconstructing methods are also discussed.