Massive plasma transport across the magnetospheric low-latitude boundary layer

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This study aims at clarifying massive plasma transport across the magnetospheric low-latitude boundary layer, which would constitute a plasma sheet formation process that is totally different from the well-known. The new transport process at low-latitude is not expected in a pure MHD model and thus would involve coupling of dynamics over decades in temporal as well as spatial scales, from MHD down to the electron scales. In order to study the transport process that results from cross-scale coupling effects, we have performed numerical simulations of MHD phenomena using two-dimensional two-fluid simulation code including finite electron inertia effects.To be specific, we have simulated a development of MHD scale vortices that grow in velocity shear layers and have studied how the coupling to the electron dynamics emrges inside the MHD scale vortex.(1) When the flow is perpendicular to the magnetic field, the vortex roll-up motion produces an intese current layer, inside of which excited is an instability due to finite electron inertia. This produces a seeding perturbation for the secondary velocity shear instability at the outer edge of the vortex, which produces smaller vortices that destroy the parent vortex.(2) When there is an in-plane magnetic component, the field lines stretched by the roll-up motion are seen to reconnect. More dynamic reconnection is observed when the vortex size is larger relative to the electron scale.In either case, coupling to electron scales are observed within highly rolled-up MHD-scale vortices and this produces new effects not obtainable within the MHD framework. It is expected that these effects would lead to massive transport across the velocity shear layer.