| Summary: | P(論文) In this paper, coronal magnetic field structures are compared with coronal holes, interplanetary plasma and magnetic fields, and geomagnetic disturbances. The comparison is made for four selected periods, two in times of low solar activity and the remaining two in high solar activity. As a result, evidence is given that open magnetic structures are formed in the solar corona during both low and high solar activity periods, and that the open field regions are the sources of corotating high-speed solar wind streams. In particular, it is shown that recurrent series of geomagnetic disturbances are seen regardless of solar activity which are well associated with the central meridian passage of long-lived open field regions. In one case, geomagnetic activity of recurrent disturbances is found to be well correlated with the evolution of the corresponding open field region. This study emphasizes the importance and usefulness of pursuing evolutionary changes in coronal magnetic structures to the study of recurrent geomagnetic disturbances. departmental bulletin paper
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