This is a fellowship project to carry out a statistical study, case studies, and simulations of electromagnetic energy transfer via ULF waves that will place important constraints on the amount of energy that can be transported via ULF waves globally and in different frequency bands. In situ estimates of the energy transfer will be made using electric and magnetic field measurements from the Time History of Events and Macroscale Interactions During Substorms (THEMIS) five satellite constellation. the results will be interpreted in terms of magnetospheric energy transfer modes using case studies and magnetohydrodynamic (MHD) simulations. The work will be conducted at the University of Michigan in the Atmospheric, Oceanic, and Space Sciences (AOSS) Department under the mentorship of Professor Mark Moldwin.
The project will have broader impacts as it includes a commitment from the team to disseminate their research to a broad audience at local K-12 schools and outreach events as well as develop new outreach materials that communicate the importance of energy transfer via ULF waves. In addition, Some ULF wave modes can interact with radiation belt electrons, creating energetic particles that pose a threat to satellites. The study of energy transfer via ULF waves, therefore, may have important societal impacts in helping to improve space weather radiation belt modeling.
The near-Earth space environment is filled with ionized gas, or plasma, which in turn is filled with a variety of plasma waves. Ultra Low Frequency (ULF) plasma waves can potentially affect technology in space and on Earth; for example, by affecting the intensity of high energy radiation belts near communication satellites in geostationary orbit. This project was aimed at determining the amount of electromagnetic energy ULF waves transport in the near-Earth space environment, using a combination of satellite measurements and computer simulations. This important measurement provides information about the location of wave energy sources and sinks and the particular types of ULF wave modes that play the most important roles in energy transfer. Through the research funded by this award, we learned the lowest frequency ULF waves are most important for energy transfer. These waves have timescales on the order of minutes and can provide an important energy input to the Earth’s ionized and neutral atmosphere in at least some circumstances. We also learned that the direction and magnitude of energy transfer depends on the local time and overall level of geomagnetic activity – the direction and magnitude of energy transfer are important as they both affect the interaction between these waves and the radiation belts. Finally, through simulations and observations we learned more about how ULF waves are generated, propagate, and evolve in time.
