GEM: The Excitation of Magnetospheric Ultra-low Frequency Waves via Solar Wind Magnetic Field Fluctuations

许多研究已经建立了太阳风参数与辐射带中电子通量增强之间的联系。然而，中间的物理机制(s)负责观察到的联系尚未明确建立。越来越多的证据表明，太阳风中的超低频率波有时可能是辐射带中电子通量增强的原因。这个项目将研究行星际磁场波动在磁层内产生极低频脉冲中所起的作用。它将使用受控的数值实验，通过使用全局的三维磁流体动力学（MHD）模拟。模拟是研究太阳风驱动的超光速脉冲的有力工具，因为真实的和合成的太阳风条件都可以用来驱动磁层。利用合成的、理想化的太阳风结构，可以分离出单个太阳风参数，以便对磁层响应进行详细研究。在该项目的第一个组成部分，MHD模拟将由理想化的单色和宽频型货币基金组织波动驱动。这些模拟将作为数值实验进行，以充分评估通过IMF波动产生的磁层极低频脉动。这些数值实验的结果将有助于解释该项目的第二个组成部分的结果，该部分将涉及具体真实事件的模拟。高能辐射带电子是对这种天基技术最严重的危害之一。这个项目将研究一类特殊的磁层波，它可能在外部辐射带产生高能电子通量增强方面发挥作用。因此，本研究具有重要的社会影响。地球空间环流模型（GGCM）的发展是美国国家科学基金会地球空间环境建模（GEM）项目的一个长期目标，本项目将通过严格和系统地使该模型受IMF波动的影响，为这种模型的发展做出贡献。

Many studies have established a link between solar wind parameters and electron flux enhancements in the radiation belts. However, the intermediary physical mechanism(s) responsible for the observed link has yet to be definitively established. There is increasing evidence that ultra-low frequency wves within the solar wind may, at times, be responsible for electron flux enhancements in the radiation belts. This project will investigate the role that interplanetary magnetic field (IMF) fluctuations play in the generation of magnetospheric ULF pulsations within the magnetosphere. It will used controlled, numerical experiments, through the use global, three-dimensional magnetohydrodynamic (MHD) simulations. Simulations can be powerful tool for studying solar wind driven ULF pulsations, since both real and synthetic solar wind conditions can be used to drive the magnetosphere. The use of synthetic, idealized solar wind configurations allows individual solar wind parameters to be isolated for detailed investigations into the magnetospheric response. In the first component of the project, MHD simulations will be driven by idealized monochromatic and broadband-type IMF fluctuations. These simulations will be conducted as a numerical experiment to fully assess the generation of magnetospheric ULF pulsations via IMF fluctuations. The results from these numerical experiments will aid in the interpretation of results from the second component of the project which will involve simulations of specific real events. Energetic radiation belt electrons are one of the most significant hazards to such space-based technologies. This project will investigate a particular class of magnetospheric waves that may play a role in creating energetic electron flux enhancements in the outer radiation belt. Thus, this research has an important societal impact. The development of a Geospace General Circulation Model (GGCM) is a long-term goal of NSF's Geospace Environment Modeling (GEM) program and this project will contribute to such model development, by rigorously and systematically subjecting the model to IMF fluctuations.