MMS Observations of an Active Flux Rope During Asymmetric Magnetic Reconnection

Abstract Within the magnetopause reconnection layer, a magnetic flux rope shows a stepped ascent in its core magnetic field. Gradients within this core field are analyzed at Magnetospheric Multiscale tetrahedron scales. We employ kinetic particle‐in‐cell (PIC) simulations to explore the formation of these stepped features, based on a multiple X‐line reconnection scenario. Simulations demonstrate the injection of magnetic flux, transported via boundary layer electron flows, into the flux rope. The transported flux forms layered configurations delimited by filamentary currents. Analysis shows that the guide field and the boundary electron jet govern transported flux strength, while Hall physics and reconnection outflows alter the core field topology. The resulting stepped core field distribution signals ongoing flux rope dynamics, providing a diagnostic signature for magnetopause flux rope activity.