Are earthward bursty bulk flows convective or field-aligned?

We use five years of Geotail and AMPTE/IRM measurements in the near-Earth magnetotail to compute angles between vectors of fast earthward plasma flow and the local magnetic field. In the low-β parts of the magnetotail, fast flows were found to be nearly field-aligned with an average angle of ~20°. In the high-β plasma sheet the average angle was larger than 45°. The existence of a substantial convective component in the plasma sheet confirms the importance of the bursty bulk flow phenomenon for the magnetotail convection process.