Simultaneously observed ion- and electron-scale quadrants of the reconnection Hall magnetic field at magnetopause

Abstract:

We investigate electron flow jets during the crossing of an ion-electron decoupling region of magnetopause reconnection event. An electron-scale current layer, originating from X-line and extending in both outflow directions, is identified on the magnetospheric side of the ion-electron decoupling region. This electron-scale current layer consists of a perpendicular current dominating at its center and field-aligned currents mainly in the boundary regions. On the magnetospheric side boundary of this layer, the inflowing electrons are streaming towards the X-line along the magnetic field while, on its magnetosheath side boundary, the outflowing electrons are ejected away from the X-line. This field-aligned electron flow system and the inflowing electrons on the magnetosheath boundary of the ion-electron decoupling region constitute an integrated Hall current system and results in a severely distorted Hall quadrupolar structure. Widths of the two quadrants adjacent to magnetosphere are electron-scale while the rest two quadrants on the magnetosheath side are ion-scale. The energy dissipation and accumulation was simultaneously occurring in the thin current layer near the X-line.