Critical Assessment of the Three-dimensional (3D) Standard Model of Solar Eruptions Using a Data-driven MagnetoHydroDynamic (MHD) Approach

使用数据驱动的磁流体动力 (MHD) 方法对太阳喷发三维 (3D) 标准模型进行批判性评估

基本信息

批准号：
1841962
负责人：
KD Leka
金额：
$ 34.15万
依托单位：
NorthWest Research Associates, Incorporated
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-05-15 至 2023-04-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1841962&HistoricalAwards=false
关键词：
Critical Assessment Three dimensional 3D

项目摘要

Theoretical models of solar eruptions are supported by numerical MHD calculations that use simple magnetic and velocity fields. The Sun, however, is much more complex, and it is therefore unclear whether models that work under ideal conditions resemble on the actual Sun. The aim of this three-year research project is to test a popular model of solar eruptions, "the standard 3D model," under realistic conditions by modeling real eruptions using photospheric observations to drive active-region-scale coronal MHD simulations. The project team will devote a significant amount of time and effort to compare their numerical simulations to real solar observations. The research study will have three parts: (i) perform data-driven MHD simulations; (ii) compare the simulations with observations; and, (iii) use the simulations to test predictions of "the standard 3D model." For a sample of eruptive regions, the project team will construct nonlinear force-free extrapolations from vector magnetograms, about an hour before each eruption. These extrapolations will be used to initialize the zero-beta MHD simulations driven by flow maps inferred from spectro-polarimetric data using optical-flow methods that treat the induction equation consistently. The team will also model a set of non-eruptive regions as an important control: they will aim to demonstrate that their method does not produce eruptions when none occurs in reality. They will use their simulations to test the predictions of "the standard 3D model" regarding the instability mechanism responsible for eruption (e.g., torus instability) and mode of reconnection during the eruption (e.g., slipping reconnection). The inclusion of control regions will indicate whether or not these features are essential for an eruption to occur, and not just simply being present but remain unimportant during the eruption process. The team will identify the instability mechanism, sites and nature of reconnection in their simulations.To date, "the standard 3D model" of solar eruptions has been tested extensively using MHD simulations with simple bipolar magnetic fields. This three-year research project takes the important next step to test the model under realistic conditions. The intellectual merit of this work is to establish the viability of "the standard 3D model." The project also aims to provide new physical insight into the basic mechanisms of magnetic energy storage and release in the solar atmosphere, which are important in a general astrophysical context. A novel aspect of the research project is the significant amount of work devoted to validating the data-driven MHD simulations; although this type of simulations is becoming increasing common in recent years, their validation is typically of a secondary consideration and it often relies on by-eye comparisons between EUV loops and field lines from the simulation, for example. The project team will devote a significant amount of time and effort to developing metrics for making quantitative comparisons between simulations and observations, which is a necessary step for objective validation.The anticipated results of this three-year project will be of interest to the space weather community: an improved understanding of solar eruptions will also improve our predictive capability for these events. The methodology and metrics for comparing numerical simulations to real observations that will be developed as part of this project will be of general use to the solar community; the project team will make their tools available to the broader community online. All their project data will be made available to the public too. The team also plans to organize a special session at the SHINE Workshop in the last year of the project focused on critically assessing the 3D standard model using different MHD models. The research and EPO agenda of this project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

太阳喷发的理论模型由使用简单磁和速度场的数值MHD计算支持。但是，太阳要复杂得多，因此尚不清楚在理想条件下起作用的模型是否类似于实际的太阳。这个为期三年的研究项目的目的是在现实的条件下测试一种流行的太阳喷发模型，即“标准3D模型”，通过使用光球观测来对实际喷发进行建模，以驱动活动区域规模的冠状MHD模拟。项目团队将花费大量时间和精力将其数值模拟与实际太阳能观察进行比较。研究研究将有三个部分：（i）执行数据驱动的MHD模拟；（ii）将模拟与观察结果进行比较；（iii）使用模拟测试“标准3D模型”的预测。对于喷发区域的样本，项目团队将在每次喷发前约一个小时内从矢量磁图中构建非线力的外推。这些外推将用于初始化由零β的MHD模拟，该模拟是由通过光学偏置数据推出的流量图驱动的光流方法始终如一地处理感应方程的。该团队还将建模一组非爆发区域作为一个重要控制：他们将旨在证明他们的方法不会在现实中没有发生时产生喷发。他们将使用模拟来测试有关导致喷发的不稳定性机制（例如，圆环不稳定性）和喷发过程中重新连接模式（例如，重新连接）的“标准3D模型”的预测。控制区域的包含将表明这些特征是否对于发生喷发至关重要，而不仅仅是在场，而且在喷发过程中仍然不重要。该团队将在模拟中确定重新连接的不稳定性机制，位点和性质。到目前为止，使用具有简单双极磁场的MHD模拟对太阳喷发的“标准3D模型”进行了广泛的测试。这个为期三年的研究项目采取了重要的下一步，在现实条件下测试该模型。这项工作的智力优点是建立“标准3D模型”的可行性。该项目还旨在提供对磁性能源存储和太阳大气中释放的基本机制的新新洞察力，这在一般的天体物理环境中很重要。研究项目的一个新方面是致力于验证数据驱动的MHD模拟的大量工作。尽管近年来，这种类型的仿真越来越普遍，但它们的验证通常是次要考虑的，并且通常依赖于模拟中的euv循环和现场线之间的比较。项目团队将花费大量时间和精力来开发指标，以进行仿真和观察之间的定量比较，这是客观验证的必要步骤。该三年项目的预期结果将使太空天气社区感兴趣：对太阳能爆发的理解也将提高我们对这些活动的预测能力。将数值模拟与将作为该项目一部分开发的实际观察结果进行比较的方法和指标将对太阳能社区普遍使用；项目团队将使他们的工具可用于在线更广泛的社区。他们的所有项目数据也将向公众提供。该团队还计划在该项目的最后一年在Shine研讨会上组织一次特别会议，重点是使用不同的MHD模型对3D标准模型进行批判性评估。该项目的研究和EPO议程支持了AGS部门在发现，学习，多样性和跨学科研究方面的战略目标。该奖项反映了NSF的法定任务，并认为值得通过基金会的知识分子优点和更广泛影响的评估标准通过评估来获得支持。