Keywords:magnetic flux rope, coronal mass ejection, polarity inversion line
The ISEST/MiniMax24 is one of the four projects of VarSITI. Its objectives and goals are to understand the propagation of solar transients through the space between the Sun and the Earth, and develop space weather prediction capability. Toward the goals the ISEST/MiniMax24 Working Group 4 organized a campaign study by selecting 11 solar-terrestrial events. We examined the solar wind data during each period of the campaign events and identified flux rope structure in 9 cases. Then geometries of 9 interplanetary flux ropes (IFRs) were determined by a model-fitting method and compared them with magnetic structures in their solar source regions. As a result, we could confirm the general coincidence between the IFR orientations and the orientations of the polarity inversion lines (PILs) in the corresponding solar source regions. The results are summarized in Table 1. This analysis result suggests a possibility for predicting variations of solar wind magnetic fields associated with flux ropes basically by observing the causative solar eruptions. However, we found several cases in which prediction needs the precise knowledge about the flux rope structure and where the Earth encounters it with a flux rope. We report the relationships between the IFRs and the corresponding PILs with emphasis upon how the observed magnetic fields are determined by the encountering geometries.