The role of small-scale features in the magnetotail in substorm development

The timing of substorm onset in relation to magnetotail dynamics is still rather controversial, particularly with regard to the link to reconnection in the tail. 3D global multi-scale/multi-fluid simulations are used to study the dynamics of the magnetotail with high (~ 400 km) resolution prior to, during, and after substorm onset. Case studies include examples of both internally and externally triggered events. Simulation results are validated against satellite data and observations of the auroral oval. Particle tracking is used to investigate how small-scale features such as kinks in the current sheet can accelerate ionospheric particles and lead to an enhancement in the ring current.