Investigation of the Causes and Effects of the Storm-Time Ion Ring Current Decay

地球环电流是在大气层上方数千英里处环绕地球流动的电流。环电流是控制轨道卫星运行的大气层上方空间条件的主要电流系统之一。这种电流可能会发生几个数量级的突然变化，导致地球表面磁场的全球减弱，称为地磁暴。因此，风暴时间环电流与有害的空间天气效应有关，这激发了对其形成，动力学和衰减的研究。由于环电流在几小时到几天的时间尺度上衰减，其能量通过损耗过程释放到空间和大气中，其对这种衰减的贡献仍然是与环电流有关的突出问题之一。本计画旨在研究环电流中的主要载子--环电流离子的暴时衰变的原因与影响。拟议的工作可大大增进我们对地球环电流动态的了解，包括其空间气象影响和相关的空间环境。此外，作为拟议活动的一部分，高中生将通过参加美国宇航局戈达德太空飞行中心的美国宇航局暑期实习计划，从最先进的科学研究中受益。由于环电流在风暴恢复阶段的几小时到几天的时间尺度上衰减，其能量通过电荷交换、库仑碰撞、场线曲率散射、与等离子体波的共振相互作用以及向向阳面磁层顶的漂移损失等损失过程释放到空间、大气和等离子体层顶。该项目解决了关于环电流衰减的未解决的科学问题。该方法将包括数值模拟和观测数据验证。在这项调查的主要建模工具将是综合内磁层电离层（CIMI）模型。这个国家的最先进的动力学模型认为必要的耦合环电流和其他等离子体种群的内磁层。将对实际风暴事件进行模拟研究，以量化各个过程如何导致环电流损失，以及相关的离子沉淀如何影响电离层电导及其对磁层的反馈。这一建模工作的预期结果是系统地量化不同损失机制的作用。实现这一量化需要一个调查模型的风暴时间环电流，占所有确定的损失机制。此外，众所周知，内磁层对不同太阳风驱动器产生的风暴有不同的反应，即，由日冕物质抛射（CME）或共同旋转的相互作用区域（CIR）驱动。因此，拟议的研究将进行系统的分析不同的离子损失过程中的相对作用的CME和CIR驱动程序的风暴和磁层电离层耦合系统的影响。因此，这项研究将推进我们目前的知识，提供一个全面的物理过程中，并导致，在太阳风driving.This奖项的不同情况下的环电流的衰减反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

The terrestrial ring current is an electric current flowing around the Earth, thousands of miles above the atmosphere. The ring current is one of the principal current systems that control conditions in the space above the atmosphere where orbiting satellites operate. Abrupt changes of several orders of magnitude in this current may occur, responsible for global decreases in the Earth's surface magnetic field, known as geomagnetic storms. The storm-time ring current is thus associated with harmful space weather effects, which motivates the study of its formation, dynamics, and decay. As the ring current decays on time scales of hours to several days, its energy is released into space and the atmosphere by loss processes, whose contribution to this decay remains one of the outstanding questions related to the ring current. This project aims to study the causes and effects of the storm-time decay of the ring current ions, which are the main carriers in the ring current. The proposed work can significantly advance our knowledge of the dynamics of the Earth's ring current, including its space weather effects and the coupled space environment. Moreover, as part of the proposed activities, high school students will benefit from state-of-the-art science research by participating in the NASA summer internship program at NASA Goddard Space Flight Center. As the ring current decays on time scales of hours to several days during the storm recovery phase, its energy is released into space, the atmosphere, and the plasmasphere by means of loss processes such as charge exchange, Coulomb collisions, field line curvature scattering, resonant interactions with plasma waves, and drift out loss to the dayside magnetopause. This project addresses unresolved science questions regarding the decay of the ring current. The methodology will consist of numerical simulations and validation with observational data. The primary modeling tool in this investigation will be the Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. This state-of-the-art kinetic model considers necessary couplings between the ring current and the other plasma populations in the inner magnetosphere. Simulation studies of actual storm events will be performed to quantify how individual processes result in ring current losses and how the associated ion precipitation affects the ionospheric conductance and its feedback to the magnetosphere. The expected result from this modeling work is a systematic quantification of the roles of the different loss mechanisms. Achieving this quantification requires an investigation that models the storm-time ring current, accounting for all the identified loss mechanisms. Furthermore, it is known that the inner magnetosphere responds distinctively to storms produced by different solar wind drivers, i.e., driven by coronal mass ejections (CMEs) or by co-rotating interaction regions (CIRs). The proposed research will thus perform a systematic analysis of the relative roles of the different ion loss processes during storms of CME and CIR drivers and the impacts on the magnetosphere-ionosphere coupled system. Consequently, this study will advance our current knowledge by providing a comprehensive view of the physical processes during, and leading to, the decay of the ring current in different contexts of solar wind driving.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.