How the IMF ByInduces a Local ByComponent During Northward IMF Bzand Characteristic Timescales

We use the Lyon‐Fedder‐Mobarry global magnetohydrodynamics model to study the effects of the interplanetary magnetic field (IMF) Bycomponent on the coupling between the solar wind and magnetosphere‐ionosphere system when IMF Bz>0. We describe the evolution of how a magnetospheric Bycomponent 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 Bycomponent. We show the radial dependence of the induced Byand compare the results to the induced Byduring southward IMF conditions. We also show the response and reconfiguration time of the inner magnetosphere to IMF Byreversals 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 Byreversals is presented. We find that the induced Byresponds within 16 min of the arrival of IMF Byat the bow shock, and it completely reconfigures within 47 min. We present a dynamic description of how Byis induced during northward directed IMFAsymmetries in magnetic energy density drives shear flowsThe magnetosphere response and reconfiguration time are comparable to southward IMF