Collaborative Research: GEM--The Upper Limit of the Earth's Outer Radiation Belt Electron Fluxes

合作研究：GEM--地球外辐射带电子通量上限

• 批准号: 2247255
• 负责人: Man Hua
• 金额: $ 37.6万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2247255&HistoricalAwards=false
• 关键词: Collaborative; Research; GEM; Upper; Limit

The Earth’s outer radiation belt electrons, also known as “killer electrons”, can pose a significant hazard to Earth-orbiting satellites and our unprecedented space-based connection-dependent society. The major acceleration mechanisms for these electrons include inward radial diffusion and local-wave particle interactions with whistler-mode chorus waves. Recent studies have demonstrated the approach of an upper limit of the fluxes of these electrons, which does not necessarily depend on the magnitude of the geomagnetic storm. However, the critical geomagnetic conditions and the underlying physical mechanisms that control this upper limit of the outer radiation belt electron fluxes still remain unknown. Assessing and forecasting the extreme case of these electron fluxes in the Earth’s outer radiation belt is important not only to the space science community but also to the space industry and economy. This proposal aims to unravel the driver and construct a prediction model for the upper limit of the Earth’s outer radiation belt electron fluxes during geomagnetically active times. The PI is an early-career female scientist and will be mentored by a senior faculty. The primary objective of this proposal is to investigate the upper limit of the Earth’s radiation belt electron fluxes. The science questions that will be answered include: (1) What are the critical geomagnetic conditions and the quantitative contributions of various geomagnetic indices to the observed flux upper limits in the Earth’s outer radiation belt using both statistical analysis and machine learning techniques? (2) What are the key input parameters in the quasi-linear diffusion simulation (e.g., wave parameters, total electron density, radial diffusion, background magnetic field) that produce higher flux upper limits driven by chorus waves? (3) What is the analytical estimate of the upper limits of fluxes that are due to local heating by whistler-mode chorus waves using quasi-linear theory and what are their correlations with the observed flux upper limits from satellite observations? To address these questions, the team will combine statistical satellite data analysis using measurements from NASA’s Van Allen Probes, numerical modeling, and an analytical approach using the quasi-linear regime and machine learning technique to identify the key factors that contribute to creating the upper limit of fluxes, and develop predictive models of the maximum outer belt electrons fluxes. The results of this project will provide insights regarding the cumulative impacts of storm and substorm activity on the radiation belt electron fluxes, the physical drivers of acceleration, and develop the necessary understanding to produce forecasting models of maximum electron fluxes in the outer radiation belt. Our proposal will have a secondary goal of exploring how we can learn to use machine learning models for scientific insight discovery.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.

地球的外部辐射带电子（也称为“杀手电子”）可能对地球轨道卫星和我们前所未有的空间基于空间的连接依赖性社会构成重大危害。这些电子的主要加速机制包括向内径向扩散和与惠斯勒模式合唱波的局部波颗粒相互作用。最近的研究表明，这些电子通量的上限的方法，这不一定取决于地磁风暴的幅度。但是，控制外辐射带电子通量的上限的临界地磁条件和潜在的物理机制仍然未知。评估和预测地球外辐射带中这些电子通量的极端情况不仅对太空科学界，而且对太空行业和经济都很重要。该提案旨在揭开驾驶员并在地球上活跃时间期间地球外辐射带电子通量上限构建预测模型。 PI是一位早期职业女科学家，将由一位高级教师考虑。该提案的主要目的是研究地球辐射带电子通量的上限。将要回答的科学问题包括：（1）使用统计分析和机器学习技术，各种地磁指数对地球外辐射带中观察到的通量上限的各种地磁指数的临界地磁条件和定量贡献是什么？ （2）准线性扩散仿真中的关键输入参数是什么（例如，波浪参数，总电子密度，径向扩散，背景磁场）会产生由合唱波驱动的较高通量上限？ （3）使用准线性理论惠斯勒模式合唱波的局部加热引起的通量上​​限的分析估计值是什么？它们与卫星观测值观察到的上限的相关性是什么？为了解决这些问题，团队将使用NASA的VAN ALLEN探针，数值建模以及使用准线性政权和机器学习技术的分析方法结合统计卫星数据分析，以识别有助于创建磁通量上限并开发最大外部外部皮带电子通量预测模型的关键因素。该项目的结果将提供有关暴风雨和实体活动对辐射带电子通量的累积影响，加速度的物理驱动因素的见解，并发展必要的理解，以产生外部辐射带中最大电子通量的预测模型。我们的建议将有一个次要目标，即探索我们如何学习使用机器学习模型进行科学洞察发现。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响审查标准来通过评估来诚实地表示支持。