Response of ionospheric disturbance dynamo and electromagnetic induction during geomagnetic storm

Abstract

During geomagnetic storms, the direct penetration of magnetospheric convection electric field and the ionospheric disturbance dynamo (IDD) take place in the ionosphere. In this paper, we studied variability of IDD and electromagnetic induction (EMI) at different latitudinal sectors during the geomagnetic storms on 7 and 8 September 2002 and 20 and 21 November 2003 with high solar wind speed due to coronal mass ejection. This investigation employs geomagnetic field components (H and Z), the geomagnetic indices (Dst, AL, and AU), solar wind speed (Vx), and interplanetary magnetic field (Bz). It was observed that the H component of geomagnetic field decreases across latitudes, and varies with Vx, Bz, Dst, AL, and AU indices throughout the difference phases of the storm. Our result demonstrated the dominance of the IDD during the nighttime compared to the daytime. This implies that neutral dynamic wind is greater at night than during the day. Higher ratio ΔZ/ΔH is observed at nighttime because of the reduction on the E region conductivity, which allowed F region electric fields to dominate.