A Survey of large, rapid solar wind dynamic pressure changes observed by Interball-1 and IMP 8

Abstract. The high time-resolution solar wind ion flux measurements from Interball-1 and IMP 8 show about one hundred large, rapid dynamic the pressure changes each year. We cataloged these events by the size and transition time of the pressure changes and present a statistical survey of these events. We find that the majority of the pressure changes of more than 1–2 nPa occur over a very short time period, on the order of a few minutes or less. Most of the large pressure changes not associated with shocks are due solely to density changes with speed remaining constant. We find that pressure balance between the thermal and magnetic pressures is not maintained across most of these events, so these events are still evolving.

Key words. Interplanetary physics (solar wind plasma)