Difference Between the Ion Gyroviscous Effect and Hall Magnetohydrodynamic Effect in the Magnetic Reconnection

We study the ion gyroviscous effect and Hall magnetohydrodynamic (MHD) effect separately using the modified MHD simulation of the magnetopause. Simulations show that the ion gyroviscous effect is on the order of a characteristic scale of ion Larmor radius and is mainly limited near the magnetosheath boundary. The Hall MHD effect is on the order of a characteristic scale of ion inertial length and occurs mainly in the central region of the current layer. The magnetic field component out of the simulation plane has a bipolar structure near the magnetosheath boundary from the ion gyroviscous effect and a quadrupole structure in the central region of the current layer from the Hall MHD effect. These results are of fundamental importance in understanding the reconnection processes in space and astrophysical plasma.