Relationship between Dst and solar wind conditions during intense geomagnetic storms

Abstract

A study of 83 geomagnetic storms during 1996-2006 has been carried out to investigate the relationship between Dst and solar wind plasma parameters during intense geomagnetic storms. The geomagnetic storms are primarily associated with two classes of drivers: the magnetic cloud and complex ejecta. It was found that magnetic cloud were drivers in 43 geomagnetic storm (~ 51.8%) while complex ejecta were responsible for 40 geomagnetic storms (~ 48.2%). The correlation between Dst and magnetic field B; and between Dst and Bs was 0.76 and 0.90, respectively for geomagnetic storms resulting from magnetic clouds. The correlation between Dst and B; and between Dst and Bs was 0.71 and 0.64, respectively for geomagnetic storms resulting from complex ejecta. Furthermore, it was shown that the correlation between the Dst and solar wind speed V for magnetic cloud and complex ejecta was 0.58 and 0.57, respectively. It was observed that the correlation between Dst and VBs for magnetic cloud and complex ejecta were 0.77 and 0.71, respectively. The present results suggest that though both classes of drivers can cause intense geomagnetic storm but magnetic cloud is more geo-effective than complex ejecta.