AI 中文总结
该研究采用EUHFORIA三维MHD模型结合锥CME模型，模拟两次朝向地球的CME与环境太阳风的相互作用，发现CME及其驱动激波形变显著，侧方遭遇的CME抵达时间差异可达16小时，为空间天气预报提供支撑。
AI 中文摘要
背景：近地环境持续受到太阳风及其内嵌瞬变事件的影响。太阳上最大的等离子体与磁场爆发是日冕物质抛射（CME），当其抵达地球时，可引发地磁暴，对高度依赖技术的社会造成干扰。目标：本研究旨在加深对CME及其驱动的激波与环境太阳风相互作用过程、以及该过程产生的时空形变如何影响空间天气预报准确性的理解。方法：研究了2020年12月7日和2021年10月28日观测到的两次朝向地球的CME；为模拟内日球层中太阳风与CME的传播，采用了最先进的三维磁流体力学（MHD）模型EUHFORIA，并结合锥CME模型，重点关注沿主传播方向（MDP）和日地连线的区域。结果：CME及其驱动激波的形变可十分显著；两次CME均在变化的背景风中传播，即便在非常接近的角距离处结构也存在差异：第一次处于轻度结构化的风中，其较强形变主要出现在远离主传播方向的区域；第二次处于更复杂的环境中，在包括主传播方向附近的不同位置形成了结构强烈的激波。结论：此类相互作用还会影响CME驱动激波的特征，如跨激波的气体压缩比；在地球观测到的以侧方遭遇的CME会受到环境太阳风的强烈影响，其抵达地球的预期时间差异可达16小时。
英文摘要
Context. The near-Earth environment is continuously impacted by the solar wind and the transients embedded in it. The largest eruptions of plasma and magnetic field at the Sun are Coronal Mass Ejections (CMEs), which, upon reaching Earth, can induce geomagnetic storms and disrupt our technologically advanced societies. Aims. We aim to improve our understanding of how CMEs and CME-driven shock waves interact with the ambient solar wind, and how the resulting deformations in time and space affect the accuracy of space weather forecasting. Methods. We studied two Earth-directed CMEs, observed on December 7, 2020 and October 28, 2021. To model the solar wind and CME propagation in the inner heliosphere, we used the state-of-the-art 3D MHD model EUHFORIA with the cone CME model, focusing on the regions along the main direction of propagation (MDP) and along the Sun-Earth line. Results. The deformations of the CME and the CME-driven shock can be significant. Both CMEs propagate in a variable background wind and are structured differently even at very close angular distances. The first, in a mildly structured wind, shows its stronger deformation predominantly away from the MDP; the second, in a more complex environment, develops a strongly structured shock at very different locations, including regions close to the MDP. Conclusions. These interactions also affect the characteristics of the CME-driven shock, such as the gas compression ratio across it. CMEs observed as flank encounters at Earth can be strongly affected by the ambient solar wind, with the expected differences in the arrival time at Earth reaching up to 16 hours.
