Three-Dimensional Global Hybrid Simulations of High Latitude Magnetopause Reconnection and Flux Ropes During the Northward IMF

When the interplanetary magnetic field (IMF) is northward, magnetic reconnection between the IMF and the geomagnetic field can occur at the high latitude magnetopause, which allows energy transfer from the solar wind into Earth's magnetosphere. In this letter, by using three-dimensional global hybrid simulations, we find that during the northward IMF, high latitude magnetic reconnection both poleward and equatorward of the cusp can occur almost simultaneously. High latitude magnetopause flux ropes (HLMFRs) with four topologies of magnetic field lines can be formed by multiple X-line reconnection. At the center of the HLMFRs, there is a decrease in the surrounding magnetic field magnitude (weak core field) and an increase in parallel temperature. When the IMF is purely northward, the HLMFRs are located at the noon-midnight meridian plane. When the IMF has a positive By component, the HLMFRs in the northern hemisphere shift duskward.