Why Do Active Regions Erupt? Modeling of Active Region from Pre-Eruptive to Eruptive Processes

太阳喷发对近地环境有重大影响，因为轰击地球的高能粒子流量增加，嵌入的磁结构影响地球磁层。这对我们在太空和地面的技术资产都产生了严重后果，包括中断远程通信，危及宇航员的安全，并损坏卫星和电网。因此，对太阳喷发和相关的日冕磁场演化的重点研究有可能揭示太阳空间天气驱动因素的潜在物理机制(S)。这个为期3年的项目旨在通过数据驱动的三维(3-D)数值模拟的方法来调查太阳喷发的物理起源。该项目还具有强大的教育成分，因为它为位于亨茨维尔的阿拉巴马大学的一名博士生和一名初级科学家提供了部分支持。因此，这个项目的研究和EPO议程支持AGS司在发现、学习、多样性和跨学科研究方面的战略目标。这个为期三年的项目旨在回答一些关于太阳喷发的物理起源和演化的基本问题，这将扩大现有关于太阳耀斑和日冕物质抛射(CME)期间的能量释放以及相关的日冕重构的知识的前沿。其基本研究目标是：(1)了解基本活动区(AR)喷发物理学；(2)提供实用工具，作为开发以物理学为基础的数据驱动的空间天气预报代码的启动模型。研究计划是利用项目团队开发的MHD-DARE模型，以及来自太阳动力学天文台(SDO)上HMI和AIA仪器的观测数据，来解决以下科学问题：(I)太阳喷发前磁场结构的基本特征是什么？(Ii)光球表面运动，包括剪切、会聚和通量抵消，如何将初始出现的磁场带入如此不稳定的结构？(Iii)磁通量绳和磁重联在触发太阳喷发中扮演着什么具体角色？(4)我们能否从磁场的拓扑和演化来理解各种耀斑/喷发过程的复杂性？(5)太阳喷发是如何在光球场上留下印记的？AR发展的这些方面将与远在太阳喷发之前和期间的日冕场的演变有关，为此，项目组将使用MHD-DARE模型进行由随时间变化的矢量磁图驱动的数值模拟。然后，分析模拟结果，得出磁场拓扑、电流、等离子体流和洛伦兹力的演变，以确定太阳喷发的主要触发机制，并将它们与相关太阳观测结果进行比较。此外，该项目团队计划通过将真实的能量方程和直接来自光球层的等离子体配置纳入日冕来进一步改进当前的模型。

Solar eruptions have significant impact on the near-Earth environment due to the enhanced flux of energetic particles bombarding the Earth and the embedded magnetic structures impacting the Earth's magnetosphere. This has serious consequences for our technological assets both in space and on the ground, including interruption of tele-communication, compromising the safety of astronauts, and damaging satellites and electric power grids. Therefore, focused investigations of solar eruptions and the associated magnetic field evolution of the solar corona have the potential to reveal the underlying physical mechanism(s) of the drivers of space weather at the Sun. This 3-year project is aimed at investigating the physical origins of solar eruptions at the Sun by means of data-driven, three-dimensional (3-D) numerical simulations. The project also has a strong educational component as it provides partial support for a Ph.D. student and a junior scientist at the University of Alabama in Huntsville. Thus, the research and EPO agenda of this project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research.This 3-year project is aimed at answering some of the fundamental questions concerning the physical origin and evolution of solar eruptions, which will expand the frontier of existing knowledge on the energy release during solar flares and Coronal Mass Ejections (CMEs) on the Sun and the associated reconfiguration of the solar corona. The underlying research objectives are: (i) understanding the fundamental active region (AR) eruptive physics; and, (ii) providing a practical tool as an initiation model for the development of a physics-based data-driven space weather prediction code. The research plan is to use the MHD-DARE model developed by the project team, together with observational data from the HMI and AIA instruments onboard the Solar Dynamics Observatory (SDO), to address the following science questions: (i) what are the basic characteristics of magnetic field configuration before a solar eruption?; (ii) how do photospheric surface motions, including shear, convergence and flux cancellation bring the initial emerged fields to such an unstable configuration?; (iii) what are the specific roles played by magnetic flux rope and magnetic reconnection in triggering solar eruptions?; (iv) can we understand the complexity of various flare/eruption process from topology and evolution of the magnetic field?; and, (v) how do solar eruptions leave imprints on the photospheric fields? These aspects of the AR development will be connected to the evolution of the coronal field long before and during a solar eruption, for which the project team will use the MHD-DARE model to carry out numerical simulations driven by the time-dependent vector magnetograms. Then, the simulation results will be analyzed to yield the evolution of the magnetic topology, electric currents, plasma flows, and Lorentz force to determine the primary triggering mechanisms of the solar eruption, and they will be compared with relevant solar observations. In addition, the project team plans to further improve the current model by including a realistic energy equation and a plasma configuration directly from the photosphere into the solar corona.