Abstract
During geomagnetic storms relativistic outer radiation belt electron
flux exhibits large variations on rapid time scales of minutes to days.
Many competing acceleration and loss processes contribute to the dynamic
variability of the radiation belts; however, distinguishing the relative
contribution of each mechanism remains a major challenge as they often
occur simultaneously and over a wide range of spatiotemporal scales. In
this study, we develop a new comprehensive model for the storm-time
radiation belt dynamics by incorporating electron wave-particle
interactions with parallel propagating whistler mode waves into our
global test-particle model of the outer belt. Electron trajectories are
evolved through the electromagnetic fields generated from the Multiscale
Atmosphere Geospace Environment (MAGE) global geospace model. Pitch
angle scattering and energization of the test particles are derived from
analytical expressions for quasi-linear diffusion coefficients that
depend directly on the magnetic field and density from the magnetosphere
simulation. Using a case study of the 17 March 2013 geomagnetic storm,
we demonstrate that resonance with lower band chorus waves can produce
rapid relativistic flux enhancements during the main phase of the storm.
While electron loss from the outer radiation belt is dominated by loss
through the magnetopause, wave-particle interactions drive significant
atmospheric precipitation. We also show that the storm-time magnetic
field and cold plasma density evolution produces strong, local
variations of the magnitude and energy of the wave-particle interactions
and is critical to fully capturing the dynamic variability of the
radiation belts caused by wave-particle interactions.