Self-consistent geomagnetic storm simulation: The role of the induced electric fields

We employ a recently developed 2-way (self-consistent) coupling between a kinetic ring current model and a 3-D plasma force-balance model to simulate the inner magnetosphere during a geomagnetic storm. We find notable differences in the self-consistent results compared to those from the kinetic model with a dipole magnetic field (with the same particle boundary conditions and electric fields). In addition to large depressions in the night-side magnetic field compared to dipolar, we also find lower density and perpendicular plasma pressure in the self-consistent case, as well as localized regions of pressure peaks and enhanced plasma beta on the night side. There is also a dichotomy between the energization of high- and low-pitch angle particles, respectively, with the latter energized significantly more than in a dipole field. Finally, we describe a method for computing the electric fields induced by the time change of the self-consistent magnetic fields; for a moderate storm, we find that while the induced electric fields are in general relatively weak compared to the convective ones, at some local times and near the peak of storm activity they can be important.