Pathways to Coronal Magnetic Energy Storage and Release

本项目科学侧重于我们对太阳能量事件及其对日球层和行星际环境的潜在影响的知识中的一个根本空白--如何从能量释放的角度评估它们的潜在大小。这个项目的独特之处在于，它使用了基于统计的方法来分析太阳活动区的特征。能够测量储存和可用的能量，并预测即将发生的事件的大小，将提高对太阳耀斑和相关现象(如日冕物质抛射和高能粒子的产生和传播)的预测能力。这些现象对依赖人类的基础设施和国家安全有直接影响，因此，预测的改进最终会使社会的大部分部门受益。该项目支持一名博士后研究员和一名代表不足的群体的成员，他们将担任导师和联合PI。这个项目的目标是了解释放储存的日冕磁能的不同途径。当储存了大量自由能时，一些活跃区域会在几个大型事件中释放它，而另一些活动区域则会在许多较小的事件中释放相同数量的能量。为什么会发生这种情况还不得而知。将使用两种互补的方法来研究这一问题：1)使用光球替代大样本事件的能量，以及2)模拟小样本事件的日冕磁场。在每种情况下，将计算每个活动区域内的分区的能量，以估计耀斑中可以释放的总自由能的比例。这将与事件的GOES软X射线通量进行比较。通过判别分析计算的验证统计将被用来确定在区分产生大事件的区域和只产生小事件的区域方面，活动区域的子区域的光球代理是否比全局代理更好。如果分析表明，分区计算的自由能与释放的能量更密切相关，这将表明场的局部构型比全局构型更重要。日冕将使用最小电流日冕模型和非线性无力场外推来模拟。对于这两个模型，将详细比较发生耀斑的可能能量释放途径，以及耀斑发射与与存储能量相关的电流的位置。这将提供对支配能量事件产生的潜在过程的洞察。

This project science focuses on a fundamental gap in our knowledge of solar energetic events and their potential impact on the heliospheric and interplanetary environment - how to evaluate their potential size in terms of energy release. This project is unique in that it uses as statistics based approach to analyze characteristics of solar active regions. Being able to measure the stored and available energy, and to predict the size of an upcoming event will improve forecasting capability for solar flares and related phenomena such as coronal mass ejections and energetic particle production and propagation. These are the phenomena with direct impacts on human-dependent infrastructure and national security, hence improvements in forecasting eventually benefits large sectors of society. This project supports a postdoctoral researcher and a member of an underrepresented group who will serve as a mentor and Co-PI. Summer inters from the REU program will also be involved.The objective of this project is to understand the different pathways to the release of stored coronal magnetic energy. When a large amount of free energy is stored, some active regions release it in a few large events, while others release the same amount of energy in many smaller events. Why this occurs is unknown. Two complementary approaches will be used to investigate this: 1) using photospheric proxies for the energy for a large sample of events, and 2) modeling of the coronal magnetic field for a small sample of events. In each case, the energy will be computed for subareas within each active region to estimate the fraction of the total free energy that can be released in a flare. This will be compared to the GOES soft X-ray flux of the events. Verification statistics computed from discriminant analysis will be used to determine whether photospheric proxies for sub-areas of an active region are better then global proxies at distinguishing regions which produce large events versus those which produce only small events. If the analysis indicates that the free energy computed for sub-areas are more closely associated with the energy released, this will indicate that the local configuration of the field is more important than the global configuration. The corona will be modeled using the Minimum Current Corona model and nonlinear force-free field extrapolations. For both models, a detailed comparison will be made of the possible energy release pathways to the flares that occurred, and the location of the flare emission to the currents associated with the stored energy. This will provide insight into the underlying processes governing the production of energetic events.