Observations on a Series of Merging Magnetic Flux Ropes Within an Interplanetary Coronal Mass Ejection

Abstract

Coronal mass ejections (CMEs) are intense solar explosive eruptions. CMEs are highly important players in solar-terrestrial relationships, and they have important consequences for major geomagnetic storms and energetic particle events. It has been unclear how CMEs evolve when they propagate in the heliosphere. Here we report an interplanetary CME consisting of multiple magnetic flux ropes measured by WIND on 25–26 March 1998. These magnetic flux ropes were merging with each other. The observations indicate that internal interactions (reconnections) within multiflux rope CME can coalesce into large-scale ropes, which may improve our understanding of the interplanetary evolution of CMEs. In addition, we speculated that the reported rope-rope interactions may also exist between successive rope-like CMEs and are important for the space weather forecasting.