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

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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.