High-resolution global magnetohydrodynamic simulation of bursty bulk flows

A high-resolution global magnetohydrodynamic simulation is conducted with the Lyon-Fedder-Mobarry (LFM) model for idealized solar wind conditions. Within the simulation results high-speed flows are seen throughout the magnetotail when the interplanetary magnetic field (IMF) is southward. Case study analysis of these flows shows that they have an enhancement in BZ and a decrease in density preceding a peak in the flow velocity. A careful examination of the structure within the magnetotail shows that these features are driven by bursts of magnetic reconnection. In addition to the case study, a superposed epoch analysis of flows occurring during a 90 min interval of southward IMF yields statistical properties that are in qualitative agreement with observational analysis of bursty bulk flows (BBFs). For the idealized simulation conditions, the most significant differences with the observational results are a broader velocity profile in time, which becomes narrower away from the center of the current sheet, and a larger density drop after flow passage. The peak BZ amplitude is larger than in observations and precedes the peak in the flow velocity. We conclude that the LFM simulations are reproducing the statistical features of BBFs and that they are driven by spatially and temporally localized reconnection events within the simulation domain.