Ring current modeling in a realistic magnetic field configuration

A 3‐dimensional kinetic model has been developed to study the dynamics of the storm time ring current in a dipole magnetic field. In this paper, the ring current model is extended to include a realistic, time‐varying magnetic field model. The magnetic field is expressed as the cross product of the gradients of two Euler potentials and the bounce‐averaged particle drifts are calculated in the Euler potential coordinates. A dipolarization event is modeled by collapsing a tail‐like magnetosphere to a dipole‐like configuration. Our model is able to simulate the sudden enhancements in the ring current ion fluxes and the corresponding ionospheric precipitation during the substorm expansion.