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

We demonstrate that the reconnection rate at the subsolar magnetopause is stronglycontrolled by the solar wind electric field and depends weakly on the local properties of the dissipationregion. Our approach is to match the solar wind and magnetospheric states in an internal boundarylayer described by the Cassak and Shay (2007, https://doi.org/10.1063/1.2795630) expression fortwo-dimensional asymmetric reconnection. Faraday's law along the Sun-Earth line determinesthe variation of the solar wind electric field from the bow shock to the magnetopause. While themagnetospheric plasma exerts some control over the reconnection rate, magnetic flux pileup in the sheathpartially 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 explainingwhy the solar wind electric field correlates well with geomagnetic indices.