Magnetic Reconnection Inside Solar Wind Rotational Discontinuity During Its Interaction With the Quasi-Perpendicular Bow Shock and Magnetosheath

Abstract

Using a three-dimensional global hybrid simulation, we investigate the formation and evolution of ion-scale magnetic reconnection inside an interplanetary rotational discontinuity (RD) owing to its interaction with the quasi-perpendicular (Q-perpendicular to) bow shock and the magnetosphere. The interplanetary magnetic field (IMF) is initially predominantly northward, while it changes to purely southward across the RD. A significantly thinned RD current layer with a width similar to ion skin depth and normal magnetic field B-n approximate to 0 is formed by a shock compression process as the RD interacts with the Q-perpendicular to shock. Magnetic reconnection thereupon takes place inside the thin RD current layer, where Hall magnetic and electric fields, reconnection electric field, and high-speed ion outflow jets are identified. Simultaneously, flux ropes form with an extension of a few ion inertial lengths. As the RD is transmitted into the magnetosheath, multiple reconnection sites lead to the formation of longer flux ropes. Moreover, magnetosheath reconnection is also found at new reconnection sites inside the RD. No reconnection is found in the Q-perpendicular to shock alone outside the RD. The flux ropes propagate poleward and tailward in the magnetosheath. In addition, magnetopause reconnection takes place under the southward IMF on the sunward side of the RD after the RD passes through the magnetopause.