Energy Modulations of Magnetospheric Ions Induced by Foreshock Transient-Driven Ultralow-Frequency Waves

Although foreshock transients can generate strong magnetospheric Pc5 ultralow-frequency (ULF) waves, whether they can modulate the energy of magnetospheric ions is still poorly understood. In this study, we analyze the strong magnetospheric ion energy modulations in a foreshock transient event on October 30, 2008, based on the magnetospheric observations by the time history of events and macroscale interactions during substorms A and D in the prenoon sector. ULF wave-induced (Formula presented.) drift accelerated the cold ions up to ∼10 keV and the enhanced ion fluxes have wave-like patterns. There is another portion of enhanced ion fluxes from ∼0.8 to ∼10 keV but with strong energy dispersions in this event. By comparing the observations and the theoretical prediction, we for the first time found that the drift-bounce resonances played a major role in modulating the energy of those ions with energy dispersions, during the interactions between the ions and the foreshock transient-driven Pc5 ULF wave with growing and damping effects.