Does the Solar Wind Electric Field Control the Reconnection Rate at Earth's Subsolar Magnetopause?

Abstract

AbstractWe demonstrate that the reconnection rate at the subsolar magnetopause is strongly controlled by the solar wind electric field and depends weakly on the local properties of the dissipation region. Our approach is to match the solar wind and magnetospheric states in an internal boundary layer described by the Cassak and Shay (2007, https://doi.org/10.1063/1.2795630) expression for two‐dimensional asymmetric reconnection. Faraday's law along the Sun‐Earth line determines the variation of the solar wind electric field from the bow shock to the magnetopause. While the magnetospheric plasma exerts some control over the reconnection rate, magnetic flux pileup in the sheath partially compensates for any local reduction in the reconnection rate. For a fixed magnetospheric state, the reconnection rate is shown to be directly proportional to the solar wind electric field, thus explaining why the solar wind electric field correlates well with geomagnetic indices.