Solar wind parameters and geomagnetic indices for four different interplanetary shock/ICME structures

Abstract

Interplanetary shocks associated with coronal mass ejections (CMEs) have very profound effects on geomagnetic storms. In order to investigate the role of the interplanetary shock properties and pre-conditions, we present a statistical study of 280 interplanetary shocks and their associated geomagnetic activities during 1998-2007. The results show that perpendicular shocks can cause more intense geomagnetic activities compared with parallel ones under the same IMF pre-condition. Through a southward IMF pre-condition, interplanetary shocks and driven ICMEs can intensify geomagnetic storms significantly. It is revealed that interplanetary shocks would intensify negative IMF Bz pre-condition by a factor of 3 to 6. This effect would enhance geomagnetic storms greatly. The result shows that there are 74% of intense (Dst ≤-100 nT) and 69% of super (Dst≤-200 nT) geomagnetic storms related to a negative IMF Bz pre-condition. © 2011 by the American Geophysical Union.