  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 coronal mass ejection (ICME)
consisting of multiple magnetic flux ropes measured by WIND on March 25-26,
1998. These magnetic flux ropes were merging with each other. The observations
indicate that internal interactions (reconnections) within multi-flux-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.
