Difference between the ion gyroviscous effect and Hall magnetohydrodynamiceffect in the magnetic reconnection

We study the ion gyroviscous effect and Hall magnetohydrodynamic (MHD) effe ct separately using the modified MHD simulation of the magnetopause. Simula tions show that the ion gyroviscous effect is on the order of a characteris tic 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 bipo lar structure near the magnetosheath boundary from the ion gyroviscous effe ct and a quadrupole structure in the central region of the current layer fr om the Hall MHD effect. These results are of fundamental importance in unde rstanding the reconnection processes in space and astrophysical plasma.