PREEVENTS Track 2: Integrated Modeling of Extreme Space Weather Events from Electron to Global Scales

空间天气是由太阳活动造成的，太阳活动会影响地球的空间环境，破坏我们的技术系统，并使飞行员和宇航员暴露在有害的辐射中。极端空间天气事件是由磁层（环绕和保护地球的磁场）的突然重新配置造成的，这是由磁重联造成的，可以认为是磁爆炸。重联发生的尺度比磁层小得多。该项目将利用一个复杂的计算机模型预测极端空间天气事件的影响。该项目将使用创新算法和最先进的模型，实现有史以来第一次对极端空间天气事件进行自洽的全球模拟，以捕捉重连的物理现象。极端的空间天气事件可能会摧毁地球上的电网，恢复时间长达数月，并在很长一段时间内大规模停电，并可能使我们的技术基础设施崩溃。 该项目的结果将允许对各种影响进行定量评估，这是预防计划和工程解决方案所需的。目前的磁层模型，包括正在过渡到诺阿空间气象建模中心运行的密歇根地球空间模型，采用的是磁流体动力学近似法，无法解释导致磁场重联的动力学过程。只有第一原理，完全动力学代码可以可靠地模拟重连，但全球动力学模拟是负担不起的当前甚至不久的将来的计算机。最近开发的MHD与嵌入式粒子在细胞（MHD-EPIC）算法提供了一个独特的解决方案。MHD代码提供了在整个计算域中的全局解，而完全动力学EPIC代码对发生重连的域的部分进行建模。MHD-EPIC比全球动力学模型更有效，这种技术已经成功地验证了几个空间物理系统，包括Ganymede，水星，火星和地球的磁层。MHD-EPIC模型将用于研究极端空间天气事件。首先，该模型将验证对观测良好的强磁暴的观测。然后，经过验证的模型将被用来模拟如果2012年7月卡林顿规模的太阳喷发没有错过地球会发生什么。理想化和按比例放大的真实的事件将被建模，以调查各种情况：极端太阳风冲压压力，磁场，持续时间和变化。对于每次运行，将计算局部表面磁场变化，并作为基于物理的电网模型的输入。

Space weather results from solar activity that can affect the space environment of Earth, damage our technological systems, and expose pilots and astronauts to harmful radiation. Extreme space weather events are caused by sudden reconfigurations of the magnetosphere, the magnetic field surrounding and protecting Earth, caused by magnetic reconnection, which can be thought of as a magnetic explosion. Reconnection happens on scales much smaller than the magnetosphere. The project will predict the effects of extreme space weather events with a sophisticated computer model. Using innovative algorithms and state-of-the-art models, the project will realize the first-ever self-consistent global simulations of extreme space weather events that capture the physics of reconnection. Extreme space weather events could knock out the power grid on Earth with a recovery time of months and the large-scale loss of electricity for an extended time and could collapse our technological infrastructure. The results of this project will allow quantitative assessment of the various impacts, which is needed for prevention plans and engineering solutions. This project supports the training of multiple graduate students.Current magnetosphere models, including the Michigan Geospace model being transitioned to operation at the Space Weather Modeling Center of NOAA, employ a magnetohydrodynamic (MHD) approximation that cannot account for the kinetic processes responsible for magnetic reconnection. Only first-principles, fully kinetic codes can reliably model reconnection, but global kinetic simulations are not affordable on current or even near-future computers. The recently developed MHD with embedded particle-in-cell (MHD-EPIC) algorithm offers a unique solution. The MHD code provides the global solution in the full computational domain, while the fully kinetic EPIC code models the parts of the domain where reconnection occurs. MHD-EPIC is much more efficient than a global kinetic model and this technique has been successfully validated for several space physics systems, including the magnetospheres of Ganymede, Mercury, Mars and Earth. The MHD-EPIC model will be employed to study extreme space weather events. First the model will be validated against observations for well-observed strong magnetic storms. Then the validated model will be used to simulate what would have happened if the July 2012 Carrington-scale solar eruption had not missed Earth. Idealized and scaled-up real events will be modeled to investigate various scenarios: extreme solar wind ram pressure, magnetic field, duration, and variability. For each run the local surface magnetic field variations will be calculated and serve as input for physics-based models of power grids.