Relative geoeffectiveness of high-speed solar wind streams from different solar sources

We study relative geoeffectiveness of the high-speed streams (HSS) coming from different sources on the Sun, identified from 16 years (1996–2011) of continuous plasma and field data. These HSS could be associated to a single coronal hole, multiple coronal holes, single coronal mass ejection, multiple coronal mass ejections, or both the coronal holes and the coronal mass ejections. We analyze the solar wind plasma and field data during the passage of the HSS, and study the relative importance of different parameters in influencing the geomagnetic activity. We apply the method of superposed epoch analysis on the geomagnetic as well as solar plasma and field data. Based on our analysis, we found that the average (Dst)min is lowest (∼20 nT) due to streams from single coronal hole and multiple coronal holes, and it is comparatively higher (∼25 nT) due to compound streams. However, as compared to single coronal hole, the (Dst)min is nearly twice (∼40 nT) and thrice (∼65 nT) due to single coronal mass ejection and multiple coronal mass ejections, respectively. We found differences in not only the magnitudes but also the time profiles and recovery characteristics of geomagnetic disturbances due to the HSS from different solar sources. We performed correlation analysis between (Dst)min and the amplitudes of various plasma/field parameters, separately, due to the HSS associated with different solar sources. We found that, during the passage of all five group of streams, the (−Bz) and/or Ey is best correlated with the Dst amplitude. However, comparatively, the relationship between the amplitudes of (−Bz) and (−Dst) is weakest (cc = 0.71) during the passage of multiple coronal holes associated stream, and the relation is strongest (cc = 0.89) during the passage of single CMEs. As regards the relationship between (Ey) and (−Dst) amplitudes, it is weakest (cc = −0.71) during multiple coronal associated streams and strongest (cc = −0.91) during streams due to multiple coronal mass ejections.