A statistical study of coronal mass ejection plasma flows

This is a report on the results of a statistical study of plasma flow characteristics before, during, and after coronal mass ejections (CMEs) observed by the instruments on board the ISEE3 spacecraft located near Earth's L1 libration point during the period 1978 to 1980. We have used parametric relationships between plasma properties (such as flow speed and proton temperature) to help distinguish between transient flow resulting from CMEs and more quiescent or quasistatic solar wind flows. A superposed epoch analysis of 29 CMEs during the period studied shows that the transient plasma flow, as we have defined it, often begins earlier and extends later than the start and end times of the CMEs based on such criteria as bidirectional flow of suprathermal electrons or energetic protons. Since the bidirectional flow is tied to the magnetic topology of the CME, our results indicate that plasma having transient flow characteristics (as we have defined them) may extend both in front of as well as behind any magnetically closed region within the CME.