A flux rope followed by recurring encounters with traveling compression regions: GEOTAIL observations

This paper reports a peculiar series of events observed with Geotail on October 24, 1992 at X ≃ −80 RE. On this day a combination of a bipolar perturbation in By and a double‐peaked perturbation in Bz, signature of a flux rope, was observed. Following this flux rope, bipolar Bz events, identifiable as Traveling Compression Regions (TCRs), were recurrently observed. The axis of the flux rope was deduced to be field‐aligned. Energetic ions (electrons) streamed earthward (tailward) in the flux rope. During the TCRs, the E×B flow showed a bipolar north‐then‐south perturbation, consistent with expected lobe plasma motion. The TCRs corresponded to weak ground magnetic disturbances and Pi2 waves. The observations can be explained by a model in which quasi‐stagnant plasmoids (Nishida et al., 1986) are recurrently generated.