Kinetic properties of bursty bulk flow events

Particle distributions of bursty bulk flow (BBF) events in the central plas ma sheet regions show that the high earthward mean velocity comes from a co mbination of energetic ion flux increases (>few keV) in the earthward direc tion and decreases of similar energy fluxes in the tailward direction. The energetic ion increases are observed to similar to few MeV during intense e vents, indicating the responsible mechanisms efficiently accelerate particl es. The BBF events are intimately tied to the dynamics of tail current shee t reconfiguration and for the two events discussed here, they occurred 45 m inutes and 5 minutes after the expansion onsets. The perception offered by our analysis differs from the earlier studies which described BBF events us ing MHD approach.