太阳爆发过程中日冕磁场的重建与分析

Solar eruptions, including solar flares, filament eruptions, and coronal mass ejections (CMEs), are the major drivers of catastrophic events in space weather. The key to understand how the eruptions are produced is to study the dynamics of the coronal magnetic field during eruptions. Due to the lack of measurements of magnetic field in the solar corona, it is usually required to reconstruct the three-dimensional (3D) coronal magnetic field from the photospheric magnetograms using numerical techniques. However, all the currently available models for coronal field reconstructions, e.g., the well-known nonlinear force-free field (NLFFF) extrapolation, can only model the quasi-static, non-erupting magnetic field, whereas the coronal magnetic field during eruptions evolves rapidly in both configuration and topology (due to magnetic reconnections). As such we propose, for the first time, to reconstruct the dynamic magnetic field during solar eruptions, basing on our data-driven MHD model for solar coronal evolutions. An advanced data-driven MHD model for reconstructing the magnetic dynamics during solar eruptions will be developed, by using the pre-eruption static NLFFF model data as the initial condition, and the time-sequence photospheric vectorial magnetic and flow fields as bottom boundary drivers. With these techniques, we will reproduce self-consistently a realistic 3D dynamic evolution for the coronal field from its initial equilibrium to lose of equilibrium and the following eruption. Further study based on these reconstructions and sophisticated topology analysis will be conducted to understand the magnetic dynamic processes and to help to interpret the EUV observations of eruptions.

太阳爆发活动是空间天气灾害性事件的主要驱动源。理解太阳爆发活动的关键在于研究爆发中发生的日冕磁场动力学过程。由于日冕磁场测量的困难性，通常需要基于物理模型并结合可观测的光球面磁场数据进行日冕三维磁场的数值重建。传统磁场重建方法如非线性无力场外推只针对于非爆发时期、接近静平衡态的日冕磁场，而爆发过程中日冕磁场位形会急剧演化，并且伴随磁重联引起的磁拓扑连接性的快速变化。为此，本项目首次提出对太阳爆发过程中动态日冕磁场进行重建，以获得爆发过程中快速演化的三维磁场。我们将以爆发前日冕磁场静态重建数据作为初始输入，进一步发展由观测数据驱动的时变三维MHD模式，尝试采用连续观测的光球磁场及流场作为边界驱动，以望模拟再现爆发源区磁场从初平衡态发展到失衡而爆发、以及爆发过程的完整自洽的动力学演变；并基于模拟结果结合多卫星多波段观测，深入分析、理解太阳爆发的磁场动力学过程，以帮助解释各种复杂的爆发观测现象。

太阳爆发活动包括太阳耀斑和日冕物质抛射是空间天气灾害性事件的主要驱动源。理解太阳爆发活动的关键在于研究爆发中发生的日冕磁场动力学过程。由于日冕磁场测量的困难性，通常需要基于物理模型并结合可观测的光球面磁场数据进行日冕三维磁场的数值重建。传统磁场重建方法如非线性无力场外推只针对于非爆发时期、接近静平衡态的日冕磁场，而爆发过程中日冕磁场位形会急剧演化，并且伴随磁重联引起的磁拓扑连接性的快速变化。本项目首次对太阳爆发过程中动态日冕磁场进行重建，获得了爆发过程中快速演化的三维磁场；并以爆发前日冕磁场静态重建数据作为初始输入，发展出了由观测数据驱动的时变三维MHD模式，并通过采用连续观测的光球磁场及流场作为边界驱动，在国际上首次实现了模拟再现爆发源区磁场从初平衡态发展到失衡而爆发、以及爆发过程的完整自洽的动力学演变；完成了对多个典型爆发事例的详细分析，促进了对各种复杂的爆发现象的理解。基于本项目的资助，我们在国际权威刊物上发表了一系列重要成果，包括1篇Nature Communications，8篇Astrophysical Journal在内的12篇SCI论文，取得了重要的国际影响力。项目主持人召开以及受邀参加多个国内外重要学术会议，显著提高了本项目研究成果的显示度和影响力。