Simulation of magnetic reconnection on the magnetopause with northward IMF and a substantial B_y component

We have studied the magnetic reconnection on the magnetopause when IMF has a northward and substantial duskward components based on a newly developed global MHD simulation model. The results suggest there are continuous and quasi-stable merging processes occurred on the magnetopause at tail-duskward of north cusp and tail-dawnward of south cusp respectively. IMF field lines are reconnected with both open lobe field lines and close terrestrial field lines. Near the north (south) cusp, the reconnected field lines with their feet in the south (north) cusp, which formed by the IMF and closed dipolar field lines, can make a second reconnection with the opened north (south) lobe field lines when they are draped tailward. This process of magnetic cycling is quite different with the model that one single IMF line is connected to both north and south lobes. Our results suggest that, double-reconnection between a single IMF line and both north and south lobe field lines cannot happen when IMF has a substantial B_y component, and thus the opened lobe field lines cannot be decreased by this process.