The solar drivers of geomagnetic disturbances during solar minimum

Recurrent high speed solar wind from coronal holes still existed around the solar minimum. Their effect on geomagnetic disturbances seems to be weak during this period. High speed solar wind sometimes overlapped with disturbances in association with coronal mass ejections (CMEs). However, a large number of geomagnetic disturbances (Dst ≤ −50 nT) were associated with CMEs even around the solar minimum of the cycle 22. The CME on 6 January 1997 was associated with the soft X-ray active region, in which there was no sunspot group and low flare activity. This region was located in the south of the recurrent coronal hole from the north pole. The observed solar wind showed a strong compression between the CME and the high speed solar wind as a result. The solar source of the CME on 6 January produced another geoeffective CME after approximately 27 days.