Abstract
AbstractWe use the Lyon‐Fedder‐Mobarry global magnetohydrodynamics model to study the effects of the interplanetary magnetic field (IMF) By component on the coupling between the solar wind and magnetosphere‐ionosphere system when IMF Bz>0. We describe the evolution of how a magnetospheric By component is induced on closed field lines during these conditions. Starting from dayside lobe reconnection, the magnetic tension on newly reconnected field lines redistribute the open flux asymmetrically between the two hemispheres. This results in asymmetric magnetic energy density in the lobes. Shear flows are induced to restore equilibrium, and these flows are what effectively induces a local By component. We show the radial dependence of the induced By and compare the results to the induced By during southward IMF conditions. We also show the response and reconfiguration time of the inner magnetosphere to IMF By reversals during northward IMF Bz . A superposed epoch analysis of magnetic field measurements from seven Geostationary Operational Environmental Satellite spacecraft at different local times both for negative‐to‐positive and positive‐to‐negative IMF By reversals is presented. We find that the induced By responds within 16 min of the arrival of IMF By at the bow shock, and it completely reconfigures within 47 min.
Highlights
The large-scale magnetospheric dynamics is primarily driven by dayside reconnection between the terrestrial magnetic field and the interplanetary magnetic field (IMF)
We use the Lyon-Fedder-Mobarry global magnetohydrodynamics model to study the effects of the interplanetary magnetic field (IMF) By component on the coupling between the solar wind and magnetosphere-ionosphere system when IMF Bz > 0
We show the response and reconfiguration time of the inner magnetosphere to IMF By reversals during northward IMF Bz
Summary
The large-scale magnetospheric dynamics is primarily driven by dayside reconnection between the terrestrial magnetic field and the interplanetary magnetic field (IMF). When the IMF is directed northward, dayside reconnection primarily takes place between the IMF and lobe field lines at or behind the cusps (Russell, 1972; Watanabe et al, 2005). This is sometimes called high-latitude reconnection due to the fact that the magnetospheric field lines map to high latitudes in the ionosphere. It is termed lobe reconnection, since the newly reconnected field lines were previously part of the magnetospheric lobe field (Crooker, 1992)
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