GEM: Multipoint Observations and Global Modeling of Energetic Particle Deep Penetration into the Low L Region of Earth's Inner Magnetosphere

了解地球周围的相对论粒子环境对于预测和缓解空间天气影响至关重要。这些影响包括对近地轨道卫星的破坏。该项目通过观测研究和最先进的建模相结合，解决了粒子如何在内部磁层加速的重要问题。这个项目的主要目标是利用Van Allen探测器和THEMIS的数据以及RCM-E和3-D粒子示踪器的建模来调查和量化电场在高能电子和质子深穿透中的作用。需要解决的具体科学问题是：1)基于多点观测，高能电子和质子对低L区的深穿透在穿透深度、频率、时间和MLT分布上有什么定量的差异？2)基于多点观测，高能粒子深穿透事件期间内磁层电场的时空演化是什么？3)RCM-E在多大程度上能代表深穿透事件期间观测到的内磁层电场？4)RCM-E给出的电场在多大程度上能够解释不同物种和/或能量的磁层内高能粒子在深穿透过程中的差异？为了回答这些科学问题，将使用Van Allen探测器的数据来识别低至L4的高能粒子深穿透事件，并将检查穿透深度、时间和MLT相关性。我们将检查Van Allen探测器上的EFW和THEMIS上的EFI的电场测量，并研究电场的时空演化。RCM-E将被用来模拟内部磁层中的自洽、时变的电场，以便与观测结果进行比较。然后，模拟的电场将被嵌入到粒子示踪器中，以检查观察到的高能粒子的深度穿透，特别是电子和质子穿透之间的差异，是否可以通过RCM-E的建模电场对内部磁层人口的传输进行解释。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding the relativistic particle environment surrounding Earth is vital to predict and mitigate space weather effects. These effects include damage to satellites in low-Earth orbit. This project addresses an important question of how particles are accelerated in the inner magnetosphere through a combination of observational studies and state-of-the-art modeling. Two early career researchers are supported.The main goal of this project is to investigate and quantify the role of electric fields in the deep penetration of energetic electrons and protons using data from the Van Allen Probes and THEMIS as well as modeling with the RCM-E and a 3-D particle tracer. Specific science questions to be addressed are: 1) Based on the multipoint observations, what are the quantitative differences between energetic electron and proton deep penetration into the low L region in penetration depth, frequency, timing, and MLT distribution? 2) Based on the multipoint observations, what is the spatiotemporal evolution of electric fields in the inner magnetosphere during energetic particle deep penetration events? 3) To what extent can the RCM-E represent the observed electric fields in the inner magnetosphere during deep penetration events? 4) To what extent can the electric fields given by RCM-E explain the differences in deep penetration of inner magnetospheric energetic particles of different species and/or energies? To answer these science questions, energetic particle deep penetration events down to L4 will be identified using data from the Van Allen Probes, and the penetration depth, timing, and MLT dependence will be examined. The electric field measurements from EFW on Van Allen Probes and EFI on THEMIS will be examined, and the spatiotemporal evolution of electric fields will be investigated. The RCM-E will be used to model self-consistent, time-varying electric fields in the inner magnetosphere to be compared to the observations. The modeled electric fields will then be embedded into a particle tracer to examine whether the observed energetic particle deep penetration, especially the differences between electron and proton penetration, can be explained by the transport of inner magnetospheric populations by the modeled electric field of RCM-E.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.