Inter-hemispheric asymmetries in the ground magnetic response to interplanetary shocks: The role of shock impact angle

Interplanetary shocks are well-known space weather phenomena that drive magnetosphere-ionosphere (MI) current systems, which in turn are associated with ground magnetic perturbations. Recent works have shown that interplanetary shock impact angles play a significant role in controlling the subsequent geomagnetic activity, where, in general, high-speed, nearly frontal shocks are more geoeffective than low-speed, highly inclined shocks. On the other hand, highly inclined shocks drive asymmetric MI responses due to asymmetric magnetospheric compressions, while almost head-on shocks drive much more symmetric MI responses. However, there are few investigations of the role of shock impact angles in driving inter-hemispheric asymmetries in the high-latitude ground magnetic response. We use data from a recently completed chain of magnetometers on the East Antarctic Plateau, combined with magnetically conjugate stations on the west coast of Greenland, to calculate the ratio of northern to southern hemisphere ground magnetic perturbation amplitudes following the impact of interplanetary shocks. We order these results according to shock impact angles obtained from a recently published database with over 500 events, and discuss how shock impact angles and speeds drive north-south hemisphere asymmetries in the ground magnetic response at high latitudes.