Simulation of interplanetary magnetic field By penetration into the magnetotail

Based on our global 3D magnetospheric MHD simulation model, we investigate the phenomena and physical mechanism of the By component of the interplanetary magnetic field (IMF) penetrating into the magnetotail. We find that the dayside reconnected magnetic field lines move to the magnetotail, get added to the lobe fields, and are dragged in the IMF direction. However, the By component in the plasma sheet mainly originates from the tilt and relative slippage of the south and north lobes caused by plasma convection, which results in the original Bz component in the plasma sheet rotating into a By component. Our research also shows that the penetration effect of plasma sheet By from the IMF By during periods of northward IMF is larger than that during periods of southward IMF