Global magnetohydrodynamic simulation of reconnection and turbulence in the plasma sheet

Abstract

Plasma sheet turbulence is examined by using a global MHD simulation. The simulation used idealized purely southward interplanetary magnetic field (IMF) driving conditions to eliminate the effect of solar wind and IMF variations. The results were compared with spacecraft observations of turbulence by computing power spectral densities and probability distribution functions. The fluctuations in the simulation were found to have properties characteristic of turbulence. The MHD simulation exhibited nested vortices on multiple scales, with the largest scales associated with reconnection outflows and the diversion of high-speed flows in the near-Earth region. The importance of strong localized reconnection regions in the simulation for driving the largest scale fluctuations supports the idea it is the main process driving turbulence in the plasma sheet. Interplay between turbulence and the reconnection process is probably present. Scaling arguments show that the scale at which turbulence is dissipated is consistent with the resistivity in the model.